4. PRODUCT CONCEPT

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NORTH ATLANTIC TREATY ORGANIZATION

ORGANISATION DU TRAITE DE L'ATLANTIQUE NORD

The NATO Product Data Model (NPDM) is a conceptual data model. It defines a common set of data definitions and data structures to support Defence System technical information management, throughout its life cycle, in the context of NATO nations and NATO industries.

The NPDM addresses the NATO requirement for data interoperability between different Information Systems by delivering a common data semantic and thus enabling consistency of interfaces at the information level without requiring standardization of hardware or software.

The NPDM uses EXPRESS, ISO 10303-11, as the modelling language to enable both human understanding and computer processing of these semantics.

NPDM version 4.10 has been developed by the NATO CALS Office (NCO) under the guidance of the NATO CALS Management Board (NCMB) with contributions from Association GOSET, France, Daimler Chrysler Aerospace (former DASA), Germany, Eurostep Limited, United Kingdom and Metasistemi S.p.A, Italy.

Intellectual Property Rights (IPR) for this document are owned by NATO. The NATO CALS Office grants permission to photocopy or otherwise reproduce this material for internal use only and under the conditions that it will remain unchanged and that ownership by the NCO is recognized. This document may not be copied for sale or profit.

Comments or observations on layout, content and future distribution of this document are welcomed by the NATO CALS Office.

Contacts

NPDM Custodian

Lt.Col. Boye Tranum tel. +32.2.707.35935 fax +32.2.707.3598

e-mail btranum@cals.nato.be

			TABLE OF CONTENT
1.	Introduction................................................................................................................			1
	1.1	General...........................................................................................................................................................		1
	1.2	Technical view..............................................................................................................................................		1
	1.3	A Brief History .............................................................................................................................................		2
	1.4	Motivation ....................................................................................................................................................		4
	1.5	Information Modeling .................................................................................................................................		4
2. How to Use the NPDM..............................................................................................				6
	2.1	Specifying Information Requirements......................................................................................................		6
	2.2	Defining a Common Vocabulary ................................................................................................................		7
	2.3	Implementing an Integrated Product Database.......................................................................................		8
	2.3.1		In the Industry .....................................................................................................................................	8
	2.3.2		In a Project .........................................................................................................................................	10
	2.3.3		In the NATO Armed Forces ............................................................................................................	10
	2.4	How to Implement the NPDM ..................................................................................................................		11
3.	Model Overview.......................................................................................................			12
	3.1	The High Level Model ..............................................................................................................................		12
	3.2	Model Organization...................................................................................................................................		13
4.	Product Concept.......................................................................................................			15
	4.1	Overview.....................................................................................................................................................		15
	4.2 Description...................................................................................................................................................			15
	4.2.1		Product Concept ...............................................................................................................................	15
	4.2.2		Specification ......................................................................................................................................	16
	4.3	EXPRESS G Diagrams ................................................................................................................................		17
	4.4	EXPRESS Syntax........................................................................................................................................		18
	4.4.1		operator ..............................................................................................................................................	18
	4.4.2		specification_operand_select .........................................................................................................	18
	4.4.3		product_concept...............................................................................................................................	18
	4.4.4		product_concept_category_association ......................................................................................	18
	4.4.5		product_concept_condition_association.....................................................................................	19
	4.4.6		product_concept_inclusion_association .....................................................................................	19
	4.4.7		product_concept_relationship .......................................................................................................	20
	4.4.8		product_concept_specification_association ...............................................................................	20
	4.4.9		specification ......................................................................................................................................	20
	4.4.10		specification_category .....................................................................................................................	21
	4.4.11		specification_expression .................................................................................................................	21
	4.4.12		specification_inclusion ....................................................................................................................	22
5. The Core Model (CoreModel) ................................................................................				23
	5.1	Overview.....................................................................................................................................................		23
	5.2	Description..................................................................................................................................................		23
	5.2.1		Product Design..................................................................................................................................	23
	5.2.2		Product Design Structure ................................................................................................................	24
	5.2.3		Product Structure for Logistic Breakdown....................................................................................	26
	5.2.4		Crossing between Breakdowns and Product Design Structure .................................................	29
	5.3	EXPRESS G Diagrams ................................................................................................................................		30
	5.4	EXPRESS Syntax........................................................................................................................................		31
	5.4.1		alias_select.........................................................................................................................................	31
	5.4.2		breakdown_type ...............................................................................................................................	31
	5.4.3		candidate_choice ..............................................................................................................................	31
	5.4.4		element_type .....................................................................................................................................	31
	5.4.5		factor...................................................................................................................................................	32
	5.4.6		indenture_level..................................................................................................................................	32

5.4.7		realisation_select ..............................................................................................................................	32
5.4.8		standard_breakdown_type .............................................................................................................	32
5.4.9		standard_element_type ...................................................................................................................	32
5.4.10		alias_identification............................................................................................................................	32
5.4.11		alternate_element_relationship.......................................................................................................	32
5.4.12		alternate_product_relationship ......................................................................................................	33
5.4.13		assembly_component_usage .........................................................................................................	33
5.4.14		assembly_component_usage_substitute .....................................................................................	33
5.4.15		breakdown..........................................................................................................................................	34
5.4.16		classification_system.......................................................................................................................	34
5.4.17		container_usage................................................................................................................................	34
5.4.18		element................................................................................................................................................	34
5.4.19		element_conversion_factor.............................................................................................................	34
5.4.20		element_definition ............................................................................................................................	35
5.4.21		element_definition_scenario_assignment ....................................................................................	35
5.4.22		element_equivalence_relationship.................................................................................................	35
5.4.23		element_group...................................................................................................................................	35
5.4.24		element_group_membership ...........................................................................................................	36
5.4.25		element_group_membership_relationship....................................................................................	36
5.4.26		element_group_relationship ...........................................................................................................	36
5.4.27		element_group_variant_relationship .............................................................................................	36
5.4.28		element_realisation ...........................................................................................................................	37
5.4.29		element_related_product_category ...............................................................................................	37
5.4.30		element_relationship ........................................................................................................................	37
5.4.31		group_member_equivalence_relationship....................................................................................	37
5.4.32		lsa_element ........................................................................................................................................	37
5.4.33		make_from_usage_option ...............................................................................................................	37
5.4.34		next_assembly_usage_occurrence ................................................................................................	38
5.4.35		non_standard_breakdown ..............................................................................................................	38
5.4.36		non_standard_element_type ..........................................................................................................	38
5.4.37		product ...............................................................................................................................................	38
5.4.38		product_category .............................................................................................................................	39
5.4.39		product_category_relationship ......................................................................................................	39
5.4.40		product_definition ............................................................................................................................	39
5.4.41		product_definition_element_relationship .....................................................................................	40
5.4.42		product_definition_relationship .....................................................................................................	40
5.4.43		product_definition_usage ...............................................................................................................	40
5.4.44		product_design_definition..............................................................................................................	40
5.4.45		product_related_product_category ...............................................................................................	41
5.4.46		product_version................................................................................................................................	41
5.4.47		product_version_relationship ........................................................................................................	41
5.4.48		promissory_usage_occurrence ......................................................................................................	42
5.4.49		quantified_assembly_component_usage .....................................................................................	42
5.4.50		realisation_application.....................................................................................................................	42
5.4.51		scenario_product_definition_assignment ....................................................................................	42
5.4.52		specified_higher_usage_occurrence.............................................................................................	42
5.4.53		sub_element_relationship ...............................................................................................................	43
5.4.54		supplied_version_relationship .......................................................................................................	43
6. Product Instance .........................................................................................................			44
6.1	Overview.....................................................................................................................................................		44
6.2	Description..................................................................................................................................................		44
6.2.1		Product Instance ...............................................................................................................................	44
6.2.2		Product Instance Identification ......................................................................................................	45
6.2.3		Product Instance Breakdown Structure .........................................................................................	46
6.2.4		Product Instance Usage History ....................................................................................................	47
6.3	EXPRESS G Diagrams ................................................................................................................................		48

	6.4	EXPRESS Syntax........................................................................................................................................		49
	6.4.1		value_select .......................................................................................................................................	49
	6.4.2		alternate_product_instance_relationship .....................................................................................	49
	6.4.3		lot_numbered_instance ...................................................................................................................	49
	6.4.4		material................................................................................................................................................	50
	6.4.5		product_instance_class...................................................................................................................	50
	6.4.6		product_instance_class_relationship ...........................................................................................	50
	6.4.7		product_instance_classification ....................................................................................................	50
	6.4.8		product_instance_definition...........................................................................................................	51
	6.4.9		product_instance_location_association.......................................................................................	51
	6.4.10		product_instance_organization_association ...............................................................................	51
	6.4.11		product_instance_physical_decomposition ................................................................................	52
	6.4.12		product_instance_relationship .......................................................................................................	52
	6.4.13		product_instance_substitution ......................................................................................................	52
	6.4.14		product_instance_usage_metrics_association ...........................................................................	53
	6.4.15		serial_numbered_instance...............................................................................................................	53
	6.4.16		usage_metrics_parameter................................................................................................................	53
	6.4.17		usage_metrics_parameter_relationship .........................................................................................	54
	6.4.18		value_list............................................................................................................................................	54
	6.4.19		value_with_unit ................................................................................................................................	54
7.	Usage Scenario .........................................................................................................			55
	7.1	Overview.....................................................................................................................................................		55
	7.2	Description..................................................................................................................................................		55
	7.2.1		Scenario and role...............................................................................................................................	55
	7.2.2		Maintenance Concept ......................................................................................................................	55
	77.2.3		Procurement Concept .......................................................................................................................	55
	7.3	EXPRESS G Diagrams ................................................................................................................................		57
	7.4	EXPRESS Syntax........................................................................................................................................		58
	7.4.1		procurement_project_name.............................................................................................................	58
	7.4.2		product_aspects ...............................................................................................................................	58
	7.4.3		location ...............................................................................................................................................	58
	7.4.4		maintenance_concept ......................................................................................................................	59
	7.4.5		maintenance_concept_assignment................................................................................................	59
	7.4.6		maintenance_level ............................................................................................................................	59
	7.4.7		operating_location............................................................................................................................	59
	7.4.8		procurement_concept ......................................................................................................................	60
	7.4.9		procurement_project ........................................................................................................................	60
	7.4.10		procurement_project_assignment..................................................................................................	60
	7.4.11		product_maintenance_level_association .....................................................................................	60
	7.4.12		provisioning_period .........................................................................................................................	61
	7.4.13		provisioning_quantity .....................................................................................................................	61
	7.4.14		recovery_method ..............................................................................................................................	61
	7.4.15		recovery_method_assignment .......................................................................................................	62
	7.4.16		role.......................................................................................................................................................	62
	7.4.17		scenario ..............................................................................................................................................	62
	7.4.18		sourcing_method ..............................................................................................................................	63
	7.4.19		sourcing_method_assignment .......................................................................................................	63
8.	Characteristics ..........................................................................................................			64
	8.1	Overview.....................................................................................................................................................		64
	8.2	Description..................................................................................................................................................		64
	8.3	EXPRESS G Diagrams ................................................................................................................................		66
	8.4	EXPRESS Syntax........................................................................................................................................		67
	8.4.1		applicability_switch..........................................................................................................................	67
	8.4.2		characteristic_assignment_type.....................................................................................................	67
	8.4.3		characteristic_target_select ............................................................................................................	68
	8.4.4		price_type ..........................................................................................................................................	68

8.4.5	qualifier_select ..................................................................................................................................	68
8.4.6	scenario_or_role ...............................................................................................................................	68
8.4.7	standard_qualifier.............................................................................................................................	68
8.4.8	achieved_availability........................................................................................................................	69
8.4.9	administrative_and_logistic_delay_time ......................................................................................	69
8.4.10	administrative_lead_time .................................................................................................................	69
8.4.11	annual_number_of_missions..........................................................................................................	69
8.4.12	annual_operation_time ....................................................................................................................	69
8.4.13	annual_usage_characteristic ..........................................................................................................	69
8.4.14	authorized_life ...................................................................................................................................	69
8.4.15	availability_characteristic ................................................................................................................	70
8.4.16	built_in_test_cannot_duplicates ...................................................................................................	70
8.4.17	built_in_test_retest_ok....................................................................................................................	70
8.4.18	characteristic......................................................................................................................................	70
8.4.19	characteristic_assignment ...............................................................................................................	70
8.4.20	currency_unit ....................................................................................................................................	71
8.4.21	detection_level..................................................................................................................................	71
8.4.22	distribution_based_period ..............................................................................................................	71
8.4.23	failure_characteristic ........................................................................................................................	71
8.4.24	failure_mode_ratio ............................................................................................................................	72
8.4.25	failure_rate .........................................................................................................................................	72
8.4.26	fault_isolation....................................................................................................................................	72
8.4.27	fault_isolation_ambiguity_group...................................................................................................	72
8.4.28	inherent_availablity..........................................................................................................................	72
8.4.29	inherent_maintenance_factor .........................................................................................................	73
8.4.30	maintainability_characteristic .........................................................................................................	73
8.4.31	maintenance_downtime ...................................................................................................................	73
8.4.32	monetary_characteristic...................................................................................................................	73
8.4.33	money_measure ................................................................................................................................	73
8.4.34	narrative_characteristic....................................................................................................................	73
8.4.35	narrative_characteristic_with_switch............................................................................................	74
8.4.36	non_standard_qualifier....................................................................................................................	74
8.4.37	operation_life.....................................................................................................................................	74
8.4.38	operational_availability....................................................................................................................	74
8.4.39	package_quantity .............................................................................................................................	74
8.4.40	period_characteristic ........................................................................................................................	75
8.4.41	point_in_time.....................................................................................................................................	75
8.4.42	price_break.........................................................................................................................................	75
8.4.43	price_characteristic_assignment ....................................................................................................	75
8.4.44	price_with_minimum_quantity .......................................................................................................	75
8.4.45	product_life........................................................................................................................................	75
8.4.46	product_price ....................................................................................................................................	76
8.4.47	property ..............................................................................................................................................	76
8.4.48	qualified_characteristic_assignment .............................................................................................	76
8.4.49	reliability_characteristic ...................................................................................................................	76
8.4.50	shelf_life .............................................................................................................................................	77
8.4.51	ship_time ............................................................................................................................................	77
8.4.52	spare_factor.......................................................................................................................................	77
8.4.53	standby_time .....................................................................................................................................	77
8.4.54	supportability_characteristic ..........................................................................................................	77
8.4.55	testability_characteristic..................................................................................................................	78
8.4.56	time_between_adaptive_maintenance_tasks ...............................................................................	78
8.4.57	time_between_corrective_maintenance_tasks ............................................................................	78
8.4.58	time_between_failure .......................................................................................................................	78
8.4.59	time_between_induced_maintenance_tasks ................................................................................	78
8.4.60	time_between_inherent_maintenance_tasks ...............................................................................	79

	8.4.61		time_between_maintenance_tasks ................................................................................................	79
	8.4.62		time_between_no_fault_found_maintenance_tasks ..................................................................	79
	8.4.63		time_between_overhauls .................................................................................................................	79
	8.4.64		time_between_perfective_maintenance_tasks ............................................................................	79
	8.4.65		time_between_preventive_maintenance_tasks ...........................................................................	80
	8.4.66		time_between_scheduled_shop_visit ...........................................................................................	80
	8.4.67		time_characteristic ............................................................................................................................	80
	8.4.68		time_to_perform_task ......................................................................................................................	80
	8.4.69		time_to_repair....................................................................................................................................	80
	8.4.70		total_life..............................................................................................................................................	80
	8.4.71		unit_of_issue.....................................................................................................................................	81
	8.4.72		wear_out_life .....................................................................................................................................	81
9.	Failure Analysis (Anomaly) .....................................................................................			82
9.1		Overview.....................................................................................................................................................		82
9.2		Description..................................................................................................................................................		82
	9.2.1		Effects .................................................................................................................................................	82
	9.2.2		Causal relationships .........................................................................................................................	83
9.3		EXPRESS G Diagrams ................................................................................................................................		85
9.4		EXPRESS Syntax........................................................................................................................................		86
	9.4.1		detection_method_category ...........................................................................................................	86
	9.4.2		probability..........................................................................................................................................	86
	9.4.3		product_anomaly_or_anomaly_in_mission_phase....................................................................	86
	9.4.4		safety_hazard_severity....................................................................................................................	86
	9.4.5		and_consequential_failure_relationship .......................................................................................	87
	9.4.6		anomaly_in_mission_phase............................................................................................................	87
	9.4.7		cause_description.............................................................................................................................	87
	9.4.8		compensating_provision .................................................................................................................	87
	9.4.9		consequence_probability ................................................................................................................	87
	9.4.10		consequential_failure_mode ...........................................................................................................	88
	9.4.11		consequential_failure_relationship ................................................................................................	88
	9.4.12		damage................................................................................................................................................	88
	9.4.13		design_provision ..............................................................................................................................	88
	9.4.14		detection_method .............................................................................................................................	88
	9.4.15		effect ...................................................................................................................................................	89
	9.4.16		failure_mode ......................................................................................................................................	89
	9.4.17		failure_mode_from_specified_source ...........................................................................................	89
	9.4.18		mission................................................................................................................................................	90
	9.4.19		mission_phase...................................................................................................................................	90
	9.4.20		mode_effect_assignment.................................................................................................................	90
	9.4.21		operator_action .................................................................................................................................	91
	9.4.22		or_consequential_failure_relationship ..........................................................................................	91
	9.4.23		other_item_effect..............................................................................................................................	91
	9.4.24		primary_failure...................................................................................................................................	91
	9.4.25		product_anomaly ..............................................................................................................................	91
	9.4.26		product_anomaly_relationship .......................................................................................................	92
	9.4.27		product_instance_anomaly .............................................................................................................	92
	9.4.28		roll_up_relationship .........................................................................................................................	92
	9.4.29		xor_consequential_failure_relationship ........................................................................................	93
10.	Task Descriptions (Task) ........................................................................................			94
10.1		Overview.....................................................................................................................................................		94
10.2		Description..................................................................................................................................................		94
	10.2.1		What to do .........................................................................................................................................	94
	10.2.2		What is used to do the job ..............................................................................................................	97
10.3		EXPRESS G Diagrams ................................................................................................................................		99
10.4		EXPRESS Syntax......................................................................................................................................		100
	10.4.1		encoded_item ..................................................................................................................................	100

10.4.2	facility_select...................................................................................................................................	101
10.4.3	hazard_values ..................................................................................................................................	101
10.4.4	information_realisation_select......................................................................................................	101
10.4.5	interval_code ...................................................................................................................................	101
10.4.6	maintenance_or_scrap_rate_select .............................................................................................	101
10.4.7	method_or_task ..............................................................................................................................	101
10.4.8	operation_type ................................................................................................................................	101
10.4.9	percentage........................................................................................................................................	102
10.4.10	resource_item ..................................................................................................................................	102
10.4.11	task_target_select...........................................................................................................................	102
10.4.12	additional_skill_requirement.........................................................................................................	102
10.4.13	advisory_task_stage ......................................................................................................................	102
10.4.14	base_task_method..........................................................................................................................	102
10.4.15	concurrent_methods ......................................................................................................................	103
10.4.16	criticality...........................................................................................................................................	103
10.4.17	decision_point.................................................................................................................................	103
10.4.18	expression_component ..................................................................................................................	103
10.4.19	encoding...........................................................................................................................................	104
10.4.20	facility_or_infrastructure ...............................................................................................................	104
10.4.21	facility_type.....................................................................................................................................	104
10.4.22	frequency_factor.............................................................................................................................	104
10.4.23	information_requirement................................................................................................................	104
10.4.24	logistic_task_method .....................................................................................................................	105
10.4.25	logistic_task_target_assignment .................................................................................................	105
10.4.26	logistics_task...................................................................................................................................	105
10.4.27	looping_method ..............................................................................................................................	106
10.4.28	maintenance_percent .....................................................................................................................	106
10.4.29	occurence_rate ................................................................................................................................	106
10.4.30	operability ........................................................................................................................................	107
10.4.31	personnel_hazard............................................................................................................................	107
10.4.32	personnel_skill ................................................................................................................................	107
10.4.33	period_measure ...............................................................................................................................	108
10.4.34	quantified_task_resource_requirement.......................................................................................	108
10.4.35	repeat_count....................................................................................................................................	108
10.4.36	repeat_until ......................................................................................................................................	108
10.4.37	repeat_while.....................................................................................................................................	109
10.4.38	scrap_on_removal ..........................................................................................................................	109
10.4.39	skill_grade........................................................................................................................................	109
10.4.40	skill_subject.....................................................................................................................................	109
10.4.41	specific_facility ...............................................................................................................................	109
10.4.42	stop_task_method ..........................................................................................................................	110
10.4.43	structured_task_method................................................................................................................	110
10.4.44	supplementary_task .......................................................................................................................	110
10.4.45	task....................................................................................................................................................	110
10.4.46	task_class.........................................................................................................................................	111
10.4.47	task_classification ..........................................................................................................................	111
10.4.48	task_call_relationship ....................................................................................................................	111
10.4.49	task_consideration .........................................................................................................................	111
10.4.50	task_function_class .......................................................................................................................	112
10.4.51	task_method ....................................................................................................................................	112
10.4.52	task_method_assignment..............................................................................................................	112
10.4.53	task_method_relationship_with_context ....................................................................................	112
10.4.54	task_method_sequence .................................................................................................................	113
10.4.55	task_relationship .............................................................................................................................	113
10.4.56	task_resource_requirement...........................................................................................................	113
10.4.57	task_resource_role .........................................................................................................................	113


10.4.58		task_target_assignment.................................................................................................................	114
10.4.59		task_training ....................................................................................................................................	114
10.4.60		test_condition .................................................................................................................................	114
10.4.61		training_location .............................................................................................................................	114
11. Technical Documentation (Information Object) ...................................................			116
11.1	Overview...................................................................................................................................................		116
11.2	Description................................................................................................................................................		116
11.3	EXPRESS G Diagrams ..............................................................................................................................		120
11.4	EXPRESS Syntax......................................................................................................................................		121
11.4.1		encoding_selection ........................................................................................................................	121
11.4.2		information_link_select..................................................................................................................	121
11.4.3		information_object_content_selection .......................................................................................	121
11.4.4		language_assignment_select........................................................................................................	122
11.4.5		reference_or_object........................................................................................................................	122
11.4.6		target_information_select..............................................................................................................	122
11.4.7		version_logic ...................................................................................................................................	122
11.4.8		base_information_object ...............................................................................................................	122
11.4.9		base_language_assignment..........................................................................................................	122
11.4.10		binary_encoded_information........................................................................................................	123
11.4.11		derivation_description ...................................................................................................................	123
11.4.12		derived_information_object..........................................................................................................	123
11.4.13		encoded_information_content .....................................................................................................	123
11.4.14		encoded_string ...............................................................................................................................	123
11.4.15		encoded_string_type ....................................................................................................................	124
11.4.16		external_document..........................................................................................................................	124
11.4.17		external_document_element..........................................................................................................	124
11.4.18		information_definition_relationship ............................................................................................	124
11.4.19		information_encoding_form..........................................................................................................	124
11.4.20		information_link..............................................................................................................................	124
11.4.21		information_object..........................................................................................................................	125
11.4.22		information_object_category ........................................................................................................	125
11.4.23		information_object_category_relationship ................................................................................	126
11.4.24		information_object_derivation .....................................................................................................	126
11.4.25		information_object_relationship ..................................................................................................	126
11.4.26		information_representation_relationship ....................................................................................	126
11.4.27		language ...........................................................................................................................................	126
11.4.28		publication .......................................................................................................................................	127
11.4.29		publication_issue............................................................................................................................	127
11.4.30		structured_information_object .....................................................................................................	127
11.4.31		text_encoded_information.............................................................................................................	128
11.4.32		versioned_information_object......................................................................................................	128
12. Configuration..........................................................................................................			129
12.1	Overview...................................................................................................................................................		129
12.2	Description................................................................................................................................................		129
12.2.1		Configuration Items ........................................................................................................................	129
12.2.2		Configuration Change ....................................................................................................................	131
12.3	EXPRESS G Diagrams ..............................................................................................................................		132
12.4	EXPRESS Syntax......................................................................................................................................		133
12.4.1		configured_specification_select ..................................................................................................	133
12.4.2		product_definition_select .............................................................................................................	133
12.4.3		solution_select ................................................................................................................................	133
12.4.4		configuration_effectivity ...............................................................................................................	133
12.4.5		configuration_item..........................................................................................................................	134
12.4.6		configuration_item_characterization ...........................................................................................	134
12.4.7		configuration_item_relationship ..................................................................................................	134
12.4.8		configuration_item_solution.........................................................................................................	135


12.4.9		dated_effectivity .............................................................................................................................	135
12.4.10		lot_effectivity ..................................................................................................................................	135
12.4.11		serial_numbered_effectivity..........................................................................................................	135
13. Work Management.................................................................................................			137
13.1	Overview...................................................................................................................................................		137
13.2	Description................................................................................................................................................		137
13.2.1		Configuration Change Control......................................................................................................	137
13.2.2		Product Instance Maintenance History ......................................................................................	138
12.3	EXPRESS G Diagrams ..............................................................................................................................		139
12.4	EXPRESS Syntax......................................................................................................................................		140
13.4.1		activity_element_select .................................................................................................................	140
13.4.2		types _of_role ..................................................................................................................................	141
13.4.3		activity ..............................................................................................................................................	141
13.4.4		activity_class...................................................................................................................................	142
13.4.5		activity_element..............................................................................................................................	142
13.4.6		activity_relationship.......................................................................................................................	142
13.4.7		adaptive_maintenance ...................................................................................................................	143
13.4.8		corrective_maintenance .................................................................................................................	143
13.4.9		logistic_activity...............................................................................................................................	143
13.4.10		perfective_maintenance .................................................................................................................	143
13.4.11		preventive_maintenance................................................................................................................	143
13.4.12		work_order.......................................................................................................................................	143
13.4.13		work_request...................................................................................................................................	144
14.	Supporting Schemas............................................................................................		145
14.1	Approval ...................................................................................................................................................		145
14.2	Person and Organization.........................................................................................................................		145
14.3	Date and Time...........................................................................................................................................		145
14.4	Contract ......................................................................................................................................................		145
14.5	Security Classification..............................................................................................................................		145
14.6	Support Resources ..................................................................................................................................		146
14.7 Referenced STEP Integrated Resources (IR).......................................................................................			146
14.8	EXPRESS G Diagrams ..............................................................................................................................		147
14.9	approval.....................................................................................................................................................		148
14.9.1		approval_assigned_item................................................................................................................	148
14.9.2		applied_approval_assignment......................................................................................................	149
14.9.3		approval............................................................................................................................................	149
14.9.4		approval_person_organization.....................................................................................................	149
14.9.5		approval_relationship ....................................................................................................................	150
14.9.6		approval_role...................................................................................................................................	150
14.9.7		approval_status ..............................................................................................................................	150
14.9.8		product_baseline_approval_assignement..................................................................................	150
14.9.9		product_design_baseline_approval............................................................................................	151
14.9.10		product_instance_baseline_approval.....................................................................................	151
14.9.11		product_requirement_baseline_approval...............................................................................	151
14.9.12		user_baseline_type ...................................................................................................................	151
14.9.13		user_defined_baseline_approval............................................................................................	151
14.10 person_and_organization.......................................................................................................................			152
14.10.1		person_oganization_select ...........................................................................................................	152
14.10.2		person_organization_assigned_items .........................................................................................	152
14.10.3		person_organization_select_with_role .......................................................................................	153
14.10.4		address .............................................................................................................................................	153
14.10.5		organization .....................................................................................................................................	154
14.10.6		organization_relationship ..............................................................................................................	154
14.10.7		organization_role ............................................................................................................................	154
14.10.8		organization_with_role ..................................................................................................................	154
14.10.9		organizational_address ..................................................................................................................	154


14.10.10		person...........................................................................................................................................	155
14.10.11		person_and_or_organization_assignment.............................................................................	155
14.10.12		person_in_organization.............................................................................................................	155
14.10.13		person_in_organization_role ....................................................................................................	156
14.10.14		person_in_organization_with_role ..........................................................................................	156
14.10.15		person_role ..................................................................................................................................	156
14.10.16		person_with_role ........................................................................................................................	156
14.10.17		personal_address .......................................................................................................................	156
14.11 date_and_time ..........................................................................................................................................			157
14.11.1 date_time_assigned_items ............................................................................................................			157
14.11.2 date_time_select .............................................................................................................................			158
14.11.3 date_time_select_with_role ..........................................................................................................			158
14.11.4 date_and_or_time_assignment ....................................................................................................			158
14.11.5 date_and_time .................................................................................................................................			158
14.11.6 date_and_time_assignment ..........................................................................................................			159
14.11.7		date_assignment .............................................................................................................................	159
14.11.8		date_role...........................................................................................................................................	159
14.11.9 date_time_role .................................................................................................................................			159
14.11.10		time_assignment .........................................................................................................................	159
14.11.11		time_role.......................................................................................................................................	160
14.12	contract.....................................................................................................................................................		160
14.12.1		contract_item...............................................................................................................................	160
14.12.2		applied_contract_assignment ..................................................................................................	160
14.12.3		contract ........................................................................................................................................	161
14.12.4		contract_assignment..................................................................................................................	161
14.12.5		contract_assignment_role .........................................................................................................	161
14.12.6		contract_role ...............................................................................................................................	161
14.12.7		contract_type ..............................................................................................................................	161
14.13	security_classification..........................................................................................................................		162
14.13.1		security_classified_items ..........................................................................................................	162
14.13.2		applied_security_classification_assignment .........................................................................	162
14.13.3		security_classification ...............................................................................................................	163
14.13.4		security_classification_assignment ........................................................................................	163
14.13.5		security_classification_assignment_role ...............................................................................	163
14.13.6		security_classification_level ....................................................................................................	163
14.13.7		security_classification_role ......................................................................................................	164
14.14	support_resources ................................................................................................................................		164

1. INTRODUCTION

1.1 General

The NATO Product Data Model (NPDM) is a formal description of the data required to support the logistics process for the acquisition and support of major systems. Such systems include aircraft, tanks and ships, and other complex products. The objective is to support the information required, used or provided by:

∙the owner of a complex product;

∙the people responsible for maintaining and repairing the product;

∙the organization(s) who design and manufacture the product.

These three groups have had equal priority. This is necessary as the contractual boundaries between them are becoming increasingly variable.

This information has been covered by several existing standards, such as MIL-STD 1388, AECMA Spec 1000D and AECMA Spec 2000M. The NPDM takes an integrated approach to the data covered by these specifications but also recognizes the possibilities for other kinds of data such as design information and multi-media. It does so in a way that should enable current approaches to be followed while enabling richer and more effective new methods to be applied.

1.2 Technical view

The NPDM is meant to be used as the basic component of an Information Technology System Architecture that supports the concept of data accessible from multiple applications and business perspectives and that may be stored in and moved between multiple Information Systems.

The NPDM may be seen as the basic element of the three-layer architecture defined by the ANSI/X3/SPARC Study Group on Database Management Systems. In particular such architecture may be described as follows:

∙The conceptual layer contains a single model, within a given context, acting as the basis for integration of data used by different applications or stored in different formats. Models in this layer must not include details that are specific to a particular application or business perspective and they must not include physical (e.g. storage) format.

∙The internal layer contains the physical model. It represents the way in which data is physically stored. There may be many valid physical models for the same conceptual model. Any physical model must be able to import data that conforms to the associated conceptual model.

∙The external layer is a view of the conceptual model from a particular perspective and for a particular application. There may be many valid external models for the same conceptual model. An external model maps to a subset of the conceptual model in such a way that the data described in the external model can be exported in the format of the conceptual model.

As part of this architecture, the NPDM has the role of conceptual layer. It defines a common set of data definitions and data structures to support Defense System technical information management, throughout the life cycle, in the context of NATO nations and NATO industries.

It is meant to be used as the platform for the development of physical and external models which are able to support data sharing and data exchange.

1.3 A Brief History

The NATO Acquisition Logistic Workshop (ALW) final report, in 1993, established the requirement for the development of the NPDM. From the ALW conclusions and recommendations:

"It is recommended that NATO assumes responsibility for the development of a consistent and stable set of data definitions ( a single data dictionary) which is applicable to land, sea and air services and manufacturing industry"

The first effort concentrated on the harmonization of the data elements contained in three input Standards (MIL-STD-1388-2B, AECMA S2000M, and AECMA S1000D). This task was completed in 1996 and the NATO CALS Data Dictionary Version 1 was consequently published. The NATO CALS Pilot Project #1 Management Group decided at that point in time to proceed with the development of a database design model (e.g. IDEF 1X or similar model).

The modeling working group used EXPRESS as the modeling language. In doing this they had the opportunity to use the state of the art in Information Technology and Data Modeling (object-oriented languages and databases, multimedia, SGML).

An important element of the approach was that some basic Integrated Resources (IR) specified within STEP were incorporated directly in the NPDM, when appropriate. This is a very important feature of the NPDM which means that data created in accordance with STEP can easily be integrated in the NPDM data set. In addition, adoption of STEP IRs will facilitate later migration to an ISO standard as recommended by the ALW.

The initial NATO Product Data Model was created over a relatively short period of time and resulted in the publication of NCDM Version 2.02 in November 1997. This version was the base for the Industrial Rig Test which performed a cross check of the model by implementing it in relational tables in a Database Application. The result of the Rig Test was a list of issues and proposals for improvement.

The NCDM Version 3.00, published in May 1998, was the result of the revision of the model on the basis of the Rig Test Report.

The NCDM Version 3.00 has proved to be an outstanding NATO CALS product. It has been world wide appreciated for its innovative concepts of integration of design data, derived from the engineering design process, and the support data produced by the Logistic Support Analysis and Failure Mode Analysis. It has influenced the work done in the product data area around the world. In particular:

∙It has provided the initial vision for the launch of the Product Life Cycle Support (PLCS) initiative.

∙It has been translated and published in Japanese by JCALS.

∙It has been the basis for the Finish Defense Information Architecture implementation.

∙It has been used as a 'reference' by the Turkish Aerospace Industries (TAI) when they developed the Turkish General Staff (TGS) Logistics System Data Model.

∙It has provided the basic concepts for the launch of the Italian MoD project (CALS Italia) which will develop a new Logistics Information System using the NPDM as its conceptual model.

∙And, finally, it has been implemented in a software prototype, founded by the French DGA, to test the model constructs and to prove that an Information System, based on a relational database, could be developed from the conceptual model.

An initiative was started in September 1999 to analyze all requirements for changes and to produce an update version of the Model. The result was the NPDM Version 4.00.

While Version 3.00 was focused on the acquisition logistics data, Version 4.00 expanded the scope of the NPDM to also include the management of Defense System Data

during the operational life. Also important is that Version 4.00 was able to capture and manage the user requirements defined in the very early stages of a program.

The NATO CALS Office has been collecting comments, issues and change proposals since the publication of NPDM Version 4.00. Morover, in August 2001, in order to insure a consistent implementation of the conceptual model across NATO, a relational model was developed (NPDM Implementation Guidelines). Based on the result of the above initiatives, a consolidated list of amendments and changes has been analised to produce an update version of

the Model. The result is the NPDM Version 4.10, which is presented in this publication.

1.4 Motivation

Modern defense systems cannot operate without access to large quantities of technical information. This information is an asset as valuable and necessary as the defense system itself.

Today, technical information is created in digital form. This behaves differently compared to information on paper. The opportunities are enormous, but new problems and risks are at the same time introduced. A major problem arises when multiple organizations need to use the same information. Differences in data definition and data format block communications between partners and require development of expensive interfaces. Too often, data is locked into the application in which it is created forcing the use of proprietary solutions. As a result, many IT systems which ought to be offering business improvement act, in practice, as barriers.

To address the above issues, the NATO Product Data Model (NPDM) defines a common set of data definitions that can be used to achieve consistency of interfaces at the information level without requiring standardization of hardware or software. The role of the NPDM is to standardize content of a life-cycle repository for defense system technical information with the objective that Armed Forces with different Information Technology infrastructure, e.g. different hardware and software platforms, can make use of the same technical information.

1.5 Information Modeling

Raw data is not information. Two parties can only exchange data in conjunction with an agreement on the meaning of the data. Consider the number “1964.” This number is data without information. The data becomes useful if we add the information that it is a year (1964), or the number of people attending the ‘98 CALS Europe Conference. Although the data is the same in both cases, the information is different.

An information model addresses the underlying meaning of data regardless of technology. A model describes meaning through structure and correctness constraints. It does not specify encoding techniques for data values.

The NATO Product Data Model uses EXPRESS as a formal language for specifying information requirements. EXPRESS is an ISO standard (ISO 10303-11) and has been used by STEP, POSC and other projects to describe the information requirements of many engineering activities.

The function of EXPRESS is to describe information requirements and correctness conditions necessary for meaningful data exchange. An EXPRESS information model is organized into schemas. The NPDM, for instance, is organized in ten schemas. These schemas contain the model definitions and serve as a mechanism for subdividing large information models. Within each schema there are three categories of definitions:

∙Entity Definitions: describe classes of real-world objects with associated properties. “product”, for instance, is an entity of the NPDM. The properties are called attributes and can be simple values, such as “name” or “id” or relationships between occurrences of entities, such as “owner” or “part of.” Entities can also be organized into classification hierarchies, and inherit attributes from super-types. The inheritance model supports single and multiple inheritance, as well as a new type, called AND/OR inheritance.

∙Type Definitions : describe ranges of possible values. The language provides several built-in types. A modeler can construct new types using the built-in types, generalizations of several types, and aggregates of values.

∙Correctness Rules: are crucial components of entity and type definitions. These local rules constrain relationships between entity instances or define the range of values allowed for a defined type. Global rules can also make statements about an entire information base.

2.HOW TO USE THE NPDM

2.1Specifying Information Requirements.

An information model is an agreement on the meaning of data. This agreement is represented in a formal manner using an appropriate descriptive language (e.g. EXPRESS). An agreement is a ‘mutual understanding or arrangement between parties’. The parties, in our case, are the Defense Industry and the NATO Armed Forces. The agreement defines WHAT data will be exchanged and what is the MEANING. In a data model the meaning of data is conveyed by the data structure and relationship. How data is created by the industry and how it is used by the single Armed Force is not part of the agreement. The processes and software applications that make use of the data are not part of the agreement either.

The NPDM can be used to specify the technical information needed by the NATO Armed Forces to support a defense system in service, through-life. From the project manager perspective, the NPDM can be used to identify data requirements for a specific project. The utilization of the NPDM in this sense is very similar to what is done today when data elements are contracted according to legacy standards (e.g. MIL STD 1388). The advantage of using the NPDM resides in the quality of the contracted data. The model gives an integrated view of data where design data like system physical and functional breakdowns are integrated with support data and with the data needed to make technical documentation available.

Text appearing as [times roman italics] in the following paragraph is provided as a sample language that can be used in developing the data requirements for a Request For Proposal (RFP) or Request for Quotation (RFQ) SOW.

ØThe contractor shall provide configuration and design data that could support the production of Bill of Material (BOM) Reports and of Labelled Occurrence, Multilevel, Indented Product Structure Reports. This data shall be in the form of instances of the following NPDM entities:

-product

-product_version

-product_design_definition and its subtypes as needed

2.2 Defining a Common Vocabulary

There is a flow of information (e.g. Defense System Technical Information) between the industry, originator of the data, and the Armed Forces, users of the same data. There could also be a need for data exchanged between Armed Forces of different NATO nations. When parties with different software and hardware platforms need to share the same information, the need for interfaces arises. These are sophisticated and expensive software that acts as ‘translators’ between different systems.

A	C
F	D

Figure 1. Number of interfaces without a common vocabulary

As illustrated in figure 1, the number of director translators between systems grows as N(N-1) where N is the number of systems. The NPDM can be used as a common vocabulary, agreed by the Defense Industry and by the NATO Armed Forces, to dramatically decrease the number of interfaces. In this case the number of interfaces only grows as 2N.

A C

NATO Product

Data Model

F D

Figure 3. Number of interfaces using the NPDM as a common vocabulary

2.3 Implementing an Integrated Product Database

A Data Model can be implemented in a database. An EXPRESS data model is technology independent and can be implemented in a variety of databases (e.g. Relational, Object Oriented, and hybrid). Unfortunately, EXPRESS does not include a construct to create relational tables automatically. A method of mapping the NPDM to a relational database was experimented during the Rig Test. Subsequentially a complete set of Implementation Guidelines for the implementation of the NPDM in a relational database have been developed and are contained in the ALP-15.

The strength of relational systems is in their ability to store large amounts of data in a highly normalized, tabular form, and to perform efficient queries across large data sets. Relational systems use SQL for both data definition and data manipulation.

Potential users of an Integrated Product Database build around the NPDM are the Industry, Defense System project teams and the NATO Armed Forces.

2.3.1 In the Industry

The need for the industry to integrate their engineering processes around integrated product database is becoming more and more evident.

Engineering applications have unusually complex information models. These information models are complex because engineering applications manipulate simulations of the real world. Models for areas such as CAD geometry, tolerances, materials, and manufacturing plans are structurally and semantically rich. Applications are similarly complex, and are tightly bound to the models. Often, the information exists only as program language structures taken from a primary application, usually a PDM or CAD system. Subsequent applications must be modified whenever the primary application changes. The resulting situation is that only special-purpose databases, controlled by PDM and CAD vendors, are used to describe complex products. Designers and Manufacturers do not have any control over their product databases, which is clearly undesirable for strategic reasons. Also, the customers’ request for complex design data together with the logistic support information in an open format accessible by off-the-shelf DBMS, is not easily addressed.

To overcome the above problems, design and manufacturing companies need to integrate their engineering processes around product databases.

CAD/CAM		PDM		LSA tools

Integrated Product

Data Base

users

Figure 4. Integrated Product Database data sources.

The term ‘integrated’ refers here to ‘the process of reconciling data from many different sources so that the resulting collection can be managed consistently with minimum redundancy’.

Some of the technical opportunities are:

∙Integration around product databases enables concurrent engineering - a process where multiple engineers work on different facets of a product concurrently;

∙An Integrated Product Database gives the opportunity to store, in a single source, information needed to deliver Technical Documentation (e.g. Technical Manuals) together with Defense System Configuration data;

∙An Integrated Product Database enables a more efficient and flexible way of delivering data to NATO Armed Forces:

−The NATO Armed Forces can be allowed to access the contractor maintained database through extensive use of web technologies;

−The database itself or part of it can be delivered to the Armed Forces as part of an Information System;

−Data can be delivered to the Armed Forces using exchange files (STEP Part 21, XML, ASCII files)

2.3.2 In a Project

A major value of an Integrated Product Database is that it can support remote access by any authorized user. The project team can make use of this feature to obtain ready access to the data while it is created. The advantages of this are obvious, for instance:

−verification that system requirements are met can be assessed in real time;

−a continuous and concurrent decision schema is enabled, thus avoiding the long delays in traditional milestone management;

−use of cross boundary integrated teams is facilitate;

−verification of database accuracy and completeness can be more easily and accurately assessed.

ØThe contractor shall provide a cost effective method of implementing an integrated product technical database based on the NATO Product Data Model such that it can be accessed by any authorised person or organisation.

2.3.3In the NATO Armed Forces

Several NATO nations are investing heavily in major IT infrastructure programs to improve logistic support for their armed forces. The NATO CALS Organization does not intend to recommend a specific hardware or software solution that all the various parties would be required to adopt and integrate with their existing infrastructure systems. Clearly, the definition and development of Information Systems is a national responsibility.

However, the NATO CALS Organization does recommend the use of the NPDM as the conceptual model for individual nation Information Systems.. The benefit of such an approach is that, through the use of the common conceptual model, data can be accessed and moved between different information systems (see paragraph 1.2), hence between different NATO nations and NATO industries. The definition of common data semantics is the NATO CALS Organization addresses the requirement of NATO information interoperability in the area of defense system technical information.

Furthermore, the NPDM, by standardizing at the information level, offers the opportunity to define an Information Infrastructure built around a ‘Defense System Technical Information Database’. The benefits of such repository of technical information for all the available weapon systems are self evident. Even more dramatic benefits could be achieved if the Defense System

Technical Information Database is implemented in a consistent way across NATO by all Nations. In this case the realization of a NATO Distributed Database for ‘Defense System Technical Information’ will be achieved. NATO Nations working together (e.g. Combined Joint Task Force) could then be allowed to access each-other weapon system technical database on a need to know basis.

2.4 How to Implement the NPDM

As said in paragraph 1.2, the NPDM could be used as an interoperability platform to develop physical models, external models, databases and Information Systems. The following diagram loosely follows IDEF0 notation and illustrates the activities required to build an IT system on top of the NPDM.

Entities/Subtypes

Attributes

Relationships

Integrity Rules

	Business Model	Create	NPDM	Business Rules
		Create
Data Requirements		Conceptual
Data Requirements		Conceptual			Attribute Formats
		Model			Attribute Formats

Tables

Columns

Keys/Indicies

Triggers

Technical Environment

Create

Empty Database

Performance Consideration

Physical

Business Processes & Funct.

Model

Populated Database

Input Data

Create &

Update Data

Software Applications

Import/Export Interfaces ( STEP/PDM)

Figure 5. Building an IT System on Top of the NPDM

The boxes in the diagram represent activities to be performed; the arrows are components of the system that should be available to perform the activities.

By delivering the NPDM, the basic component of the system, the first activity is completed. A common 'vocabulary' is in place. All the other components are grounded on the NPDM but are equally essential and need to be developed by the organizations willing to implement the Information System. It should be stressed that, to achieve interoperability between programs and between NATO Armed Forces, it is mandatory that the NPDM is used as the conceptual model in the development of national IT solutions.

3.MODEL OVERVIEW

3.1The High Level Model

A very basic simplified view of the NATO Product Data Model is shown below.

The diagram loosely follows the conventions of the EXPRESS-G language (formally defined in ISO 10303-11). For the present purposes, the diagram can be read as follows:

∙Boxes represent things of interest.

∙Thick black lines represent “is a” relationships, so “funtional_design” is a “product_design”.

∙Thin lines represent relationships or associations and are labelled to give meaning. They can often be read as a sentence, such as “product_concept”-“is defined by”- “specifications”.

configuration

person_and_organization

work_management

info_

date_

object

and_

time

approval		security_classification		contract

Figure 6. Abstract View of the NPDM

This can be interpreted as follows:

∙The product concept is, normally, the first object to be created. It is identified in the very early stage of the life cycle of the system and is described by the user-defined specifications.

∙The product design, based on product concept specifications, includes the functional design and the physical design.

∙Concurrently with the system design, the failure analysis (anomaly) is conducted to determine what can go wrong with the system and what has to be done (task) to either repair it or prevent problems from occurring.

∙A product instance is the result of the manufacturing process where one single design is realised in one or many product instances. Maintenance status and usage monitoring are needed to optimise system support activities and to plan its operational deployment.

∙The continuous processes of configuration identification and configuration change will impact different data objects identified as configuration items.

∙Any kind of additional information can be connected to aspects of the system data. Possible information types include: engineering and other drawings, video, sound, SGML files. These are, in the NPDM terminology, information objects. They may be linked to most data objects. Collection of Information Objects may be identified as publication (maintenance and other manuals, part catalogue, etc).

∙Approval may be assigned to most data objects and primarily to those that are configuration items. A type of approval is the baseline approval.

∙Person and/or organisation with role (designer, manufacturer, owner, driver, etc) and date and time with role may also be assigned to different data objects.

3.2 Model Organization

The NPDM Version 4.10 includes sixteen schemas covering the following areas:

∙Product Concept and Specifications (Product_Concept_Schema)

∙Product Design, Product structure and Breakdown (Core_Model_Schema);

∙Product Instance (Product_Instance_Schema)

∙Usage Concept (Scenario_and_Maintenance_Schema)

∙Logistic Support Analysis (Characteristics_Schema);

∙Failure Analysis (Anomaly_Schema);

∙Task Definition (Task_Schema);

∙Technical Documentation (Information_Object_Schema);

∙Configuration Item (Configuration_Schema);

∙Configuration changes and logistic activities (Work Management_Schema);

∙Approval and Approval Role (Approval_Schema);

∙Person and Organizations (Person_and_organization_Schema);

∙Date and Time (Date_and_time_Schema);

∙Contract (Contract_Schema)

∙Security Classification (Security_Classification_Schema_)

∙Support Resources (Support_resources_Schema).

In the very early phases of a project a product is just an idea (a product concept) described by its expected features and functionality. The definition of product in this case would be "the idea or concept of a thing or substance that may be designed and produced by natural process or manufacture to meet the customer requirements". From the design process perspective, later in the life cycle, a product would be "the design of a thing or substance that may be produced by natural process or manufacture". And, finally, following the manufacturing process, and during its operational life a product would be “a thing or substance produced by natural process or manufacture”.

The three definitions above reflect three different life cycle views of a product, the asrequired, the as-designed and the as-built/as-used views. To deal with these different views, the NPDM does not take the STEP approach to generalise the multiple life-cycle views under the single concept of product.

The NPDM re-use the STEP product data definitions and constructs (e.g. product, product_definition_formation, product_definition etc.) to manage the AS-DESIGNED view. The AS-REQUIRED view is covered by the Entity product_concept and its associated specification while the AS-BUILT/AS-USED view is managed by dedicated data structures collected under the Entity product_instance_definition.

In the NPDM, the three views have a very loose relationship: each one of the three may exist without the others. This approach allows for implementation flexibility of the model in different business context and scenarios (e.g. an organization manages a product instance but doesn't own the product design). However, the expected cardinalities, in an ideal implementation, are that (1) a product_concept is related to zero, one or many product_design(s) (inverse: one product_design is the solution for exactly one product_concept); (2) a product_design is related to zero, one or many product_instance(s) (inverse: a product_instance is the realization of exactly one product_design).

*of_product

product_version

of_version

definition

4.1 Overview

The Product Concept schema deals with:

∙Product Concept;

∙Specification.

4.2Description

4.2.1 Product Concept

A product concept is the idea of a product as conceived by the user. Definition of Product concepts will often be driven by user’s needs and by the user defined usage scenario. It represents the idea of a product based on the user viewpoint. The basic relationships are showed in the simplified Express G.

relating

3,4

scenario_context

product_concept

product_concept_

scenario

relationship

associated_product_concept

product_concept_	product_concept_	product_concept_	product_concept_
category_	specification_	condition_	inclusion_
association	association	association	association

Figure 4.1 Product Concept and Related Entites

A product_concept is defined within a specific context or scenario. This relationship is a many-to-many since the same product_concept may have many usage scenarios and a usage scenario may apply to many different product_concept(s).

4.2.2 Specification

Product Concepts are characterized by the user defined specifications. A specification may be a characteristic of more than one product_concept using the Entity product_concept_specification_association.

specification

specification_ inclusion

	included_specification	if_condition
category	specification_
	operand_select
		operand S[1:?]
specification_	specification_
category	expression

Figure 4.2 Specification and Specification Category

A specification refers to a specification_category that completes the semantics of the specification. Examples: 'red', 'blue', 'yellow' are specifications belonging to the specification_category 'color'; 'disk brake' and 'drum brake' are examples for specifications belonging to the specification_category 'braking system'.

A specification_expression is a combination of specification objects formed by Boolean operations. The attribute operation specifies the kind of Boolean operation. Four kinds of operations are permitted:

−'and': All of the identified specification objects shall be used;

−'or': A subset or all of the identified specification objects shall be used;

−'oneof': Exactly one of the identified specification objects shall be used;

−'not': The identified specification shall not be used.

4.3 EXPRESS G Diagrams

3,1

3,3

identifier

label

*version_id

*id

level_type

name

3,2

description

relating

description

3,2

text_select

3,4

scenario_context

product_concept

product_concept_

scenario

3,3

name

relationship

relation_type

3,3

label

associated_product_concept

condition_type

description

3,3

3,2

label

text_select

mandatory

product_concept_

BOOLEAN

category_

specification_

condition_

inclusion_

description

association

associated_category

association_type

associated_specification

associated_condition

associated_inclusion

2,2

3,3

2,1

2,3

2,4

specification_category

label

specification

specification_expression

specification_inclusion

PRODUCT_CONCEPT_SCHEMA EXPRESS-G diagram 1 of 3

		2,1(1)
	3,1	3,1
	identifier	identifier
	*id	*version_id
BOOLEAN	package
BOOLEAN	specification
	description	name
	3,2	3,2
	text_select	text_select
		category

implicit_exclusive_condition	specification_
BOOLEAN	category
	category
*id	name
3,1	3,2
identifier	text_select
	2,2(1)

	2,4(1)
3,1	3,2
identifier	text_select
*id	description

specification_ inclusion

included_specification if_condition

specification_ operand_select

operand S[1:?]

specification_ operation operator expression

*id	description
3,1	3,2
identifier	text_select
	2,3(1)

PRODUCT_CONCEPT_SCHEMA EXPRESS-G diagram 2 of 3

SUPPORT_RESOURCES_SCHEMA.text_select

3,2(1,2)

SUPPORT_RESOURCES_SCHEMA.identifier

3,1(1,2)

SUPPORT_RESOURCES_SCHEMA.label

3,3(1)

SCENARIO_AND_MAINTENANCE_SCHEMA.scenario

3,4(1)

PRODUCT_CONCEPT_SCHEMA EXPRESS-G diagram 3 of 3

4.4 EXPRESS Syntax

SCHEMA PRODUCT_CONCEPT_SCHEMA;

REFERENCE FROM SCENARIO_AND_MAINTENANCE_SCHEMA (scenario);

REFERENCE FROM SUPPORT_RESOURCES_SCHEMA (text_select,

identifier,

label);

4.4.1 operator

TYPE operator = ENUMERATION OF (AND_operator,

NOT_operator, ONEOF_operator, OR_operator);

END_TYPE;

4.4.2 specification_operand_select

TYPE specification_operand_select = SELECT (specification,

specification_expression); END_TYPE;

4.4.3 product_concept

A product_concept is the idea of a product as defined by the customer needs. The product_concept and its required features may be identified as configuration_item. A product_concept may be characterized by a set of product features identified by the customer or derived from customer's needs (e.g. specifications).

ENTITY product_concept;

name	: label;
id	: identifier;
description	: OPTIONAL text_select;
level_type	: OPTIONAL label;
version_id	: identifier;
scenario_context	: scenario;
UNIQUE
UR1: id, version_id;
END_ENTITY;
name:	The label by which the product_concept is known.
id:	The identifier that distinguishes the product_concept.
description:	An optional text that provides further information about the
	product_concept.
level_type:	Text that specifies the level of this product_concept in a
	hierarchical structure of product_concept objects.
version_id:	The identifier of the version of the product_concept.
scenario_context:	The scenario in which the product_concept is defined.

4.4.4 product_concept_category_association

A product_concept_category_association is the association of a specification_category with a product_concept. Additionally, this assignment specifies if the usage of one or more specification objects belonging to this specification_category, is mandatory or optional for all products of that product_concept.

ENTITY product_concept_category_association;

associated_category		: specification_category;
associated_product_concept		: product_concept;
mandatory : BOOLEAN;
END_ENTITY;
associated_category:	The associated_category specifies the specification_category
	that is associated with the product_concept.

associated_product_concept: The associated_product_concept specifies the product_concept

	for which the specification_category is valid.
mandatory:	The mandatory specifies whether one or more specification
	objects of the associated specification_category have to be used
	or may be used (optional) for products within the referenced
	product_concept. A value of 'true' indicates that the usage is
	mandatory. EXAMPLE: The specification category 'radio' may
	be associated 'optional' to the product concept of a tank; the
	specification category 'engine' is an example for a 'mandatory'
	association.

4.4.5 product_concept_condition_association

A product_concept_condition_association is the association of a specification_expression with a product_concept. This association includes the information that a particular specification_expression is valid for all products of that product_concept. The meaning of this association is specified further by the attribute condition_type .

ENTITY product_concept_condition_association;

condition_type		: label;
associated_product_concept		: product_concept;
associated_condition		: specification_expression;
description		: OPTIONAL text_select;
END_ENTITY;
condition_type:	The condition_type specifies the meaning of the association.

associated_product_concept: The associated_product_concept specifies the product_concept

	for which the specification_expression is valid.
associated_condition:	The associated_condition specifies the specification_expression
	that is assigned to the product_concept.
description:	The description specifies additional information about the
	product_concept_condition_association.

4.4.6 product_concept_inclusion_association

A product_concept_inclusion_association is the assignment of a specification_inclusion to a product_concept. This assignment implies that the specification_inclusion applies for all products of that product_concept.

ENTITY product_concept_inclusion_association;

associated_inclusion	: specification_inclusion;
associated_product_concept	: product_concept;
description	: OPTIONAL text_select;
END_ENTITY;

associated_inclusion:	The associated_inclusion specifies the specification_inclusion
	that is associated with the product_concept.

associated_product_concept: The associated_product_concept specifies the product_concept

	for which the specification_inclusion is valid.
description:	The description specifies additional information about the
	product_concept_inclusion_association.

4.4.7 product_concept_relationship

A product_concept_relationship is an association between two product_concept objects.

ENTITY product_concept_relationship;

relating	: product_concept;
related	: product_concept;
description	: OPTIONAL text_select;
relation_type	: label;
name	: OPTIONAL label;

END_ENTITY;
relating:	The relating specifies the first of the two product_concept objects
	related by the product_concept_relationship. The semantics of
	this attribute are defined by the attribute relation_type.
related:	The related specifies the second of the two product_concept
	objects related by the product_concept_relationship. The
	semantics of this attribute are defined by the attribute
	relation_type.
description:	The description specifies additional information about the
	product_concept_relationship. The description need not be
	specified for a particular product_concept_relationship.
relation_type:	The relation_type specifies the meaning of the relationship.
name:	The word or group of words by which the
	product_concept_relationship is known.

4.4.8 product_concept_specification_association

A product_concept_specification_association is an association of a specification with a product_concept.

ENTITY product_concept_specification_association;

associated_product_concept	: product_concept;
association_type	: label;
associated_specification	: specification;

END_ENTITY;

associated_product_concept: The associated_product_concept specifies the product_concept

	for which the specification is valid.
association_type:	The association_type specifies the kind of availability of a
	particular Specification in a product_concept.
associated_specification:	The associated_specification specifies the Specification that is
	associated with the product_concept.

4.4.9 specification

A specification is a characteristic of a product. A specification refers to a specification_category that completes the semantics of the specification.

ENTITY specification;

id	: identifier;
name	: OPTIONAL	text_select;
description : OPTIONAL		text_select;

category		: specification_category;
version_id		: identifier;
package		: BOOLEAN;
UNIQUE
UR1	:	id, version_id;
END_ENTITY;
id:		The id specifies the identifier of the specification. It shall be
		unique within the scope of a specification_category.
name:		The name specifies the word or group of words by which the
		specification is referred to.
description:		The description specifies additional information about the
		specification.
category:		The category specifies the specification_category that completes
		the semantics of the specification.
version_id:		The version_id specifies the identification of a particular version
		of a specification.
package:		The package specifies whether this specification represents a
		package of specification objects or not.

4.4.10 specification_category

A specification_category is the definition of a set of specification objects serving the same purpose.

ENTITY specification_category; implicit_exclusive_condition : BOOLEAN;

id	: identifier;
name	: text_select;
UNIQUE
UR1:	id;
END_ENTITY;
implicit_exclusive_condition: The implicit_exclusive_condition specifies whether the
	Specification objects within the specification_category are
	mutually exclusive for the production of one particular product.
	A value of 'true' indicates that the referenced objects are mutually
	exclusive for the production of the particular product.
id:	The id specifies the identifier of the specification_category.
name:	The name specifies the word or group of words by which the
	specification_category is referred to.

4.4.11 specification_expression

A specification_expression is a combination of specification objects formed by Boolean operations.

ENTITY specification_expression;

description		: OPTIONAL text_select;
operation		: operator;
operand		: SET [1:?] OF specification_operand_select;
id		: identifier;
UNIQUE
UR1	:	id;
END_ENTITY;
description:		The description specifies additional information about the

specification_expression.

operation:	The operation specifies the kind of Boolean operation. Four
	kinds of operations are permitted: AND, OR, ONEOF, NOT.
operand:	The operand specifies the operands of the Boolean operation that
	are either Specification objects or other specification_expression
	objects.
id:	The id specifies the identifier of the specification_expression.

4.4.12 specification_inclusion

A specification_inclusion is the representation of the statement that specifies that the application of a specification or of a specification_expression implies the inclusion of an additional specification or specification_expression.

ENTITY specification_inclusion;

if_condition		: specification_operand_select;
included_specification : specification_operand_select;
description		: OPTIONAL text_select;
id		: identifier;
UNIQUE
UR1	:	id;
END_ENTITY;
if_condition:		The if_condition specifies the Specification or the
		specification_expression that serves as the condition for the
		inclusion.
included_specification:		The included_specification specifies the specification or the
		specification_expression objects that are to be included.
description:		The description specifies additional information about the
		specification_inclusion.
id:		The id specifies the identifier of the specification_inclusion.

END_SCHEMA/-- PRODUCT_CONCEPT_SCHEMA

5.THE CORE MODEL (CORE MODEL)

5.1Overview

The core of the model centers on the following:

∙Product Design;

∙Product Design Structure;

∙Product Structure for Logistic Breakdown ;

∙Crossing between Breakdowns and Product Design Structure .

5.2Description

5.2.1 Product Design

The starting point is STEP Entity product. From STEP the NPDM follows the convention that the product entity represents the core concept of a product design, i.e. its identity, and not the information which is associated with the product. Such information includes the identification, any versions, and any more information which defines some things about the product. These two concepts are handled as separate entities. This gives the starting point for the model as below:

Figure 5.1 The Product Entities

This enables there to be many versions of a product and many definitions for that one product. The latter is reasonable because a product_definition is taken to be a collection of data that defines the product design for a given purpose. Hence we may have several different product definitions for logistics purposes.

In fact two different kinds of product definition are allowed for in the NPDM. One of these is aligned with the STEP standard. With this approach the relationships of an assembly to its parts are captured explicitly so the product definition for any assembled part becomes a network of related product definitions. The other type of product definition is common in logistics, where a single breakdown is used for a product/system and all its constituent parts/functions. It is important to note that the NPDM does not require one form over the other, nor does one have to be created before the other.

5.2.2 Product Design Structure

This part of the model is taken with a small number of changes from STEP integrated resources (ISO 10303, parts 41 and 44). The main part of the model defines a network of related product definitions, where the definition of an assembly is linked to the product definitions of the parts used in the assembly through the product_definition_usage entity.

relating_product_definition

2,2

product_

product_design_definition

definition_

related_product_definition

relationship

2,2

product_design_definition

quantified_

assembly_

supplied_

product_

component_

usage

version_

definition_usage

relationship

assembly_

make_from_

*base

container_usage

usage_option

component_

*substitute

component_

usage

usage_substitute

*upper_usage

promissary_

next_

*next_usage

specified_

assembly_

usage_

higher_usage_

usage_

occurrence

Figure 5.2 EXPRESS-G of Product Design Structure

In practice, assembly is almost always handled using the next_assembly_usage_occurrence entity. This captures the fact that one part (or rather a product_definition for the part) is used as a component in an assembly (or rather the product_design_definition of the assembly). Graphically this can be seen below.

Main assembly

Major subassemblies

Figure 5.3 Product Design Structure Presented as a Tree

The name attribute of the next_assembly_usage_occurrence should be used to hold an identifier for the particular place where a component is used. (This corresponds to the use of two different LCN’s to deal with, for example, the Left and Right placements for a pump used twice in the same engine.) This situation is shown in the figure below where two next_assembly_usage_occurrence entities point down to the same component.

SPD


NAUO		NAUO
NAUO	NAUO	NAUO

SPD SPD SPD

NAUO	NAUO	NAUO	NAUO	NAUO	NAUO
	NAUO		NAUO		NAUO

Figure 5.4 An Instance of a Product Design Structure

5.2.3 Product Structure for Logistic Breakdown

There are several different breakdowns used for logistics purposes. These include:

−Physical

−Functional

−System

−Zonal

−… and others

All of these basically define a hierarchy and are treated the same way in the NPDM. The starting point is the breakdown entity (a kind of product definition) which identifies the specific breakdown by name and description (all product definitions have these) and gives the type of breakdown (e.g. “functional”). A number of standard types are allowed for in the NPDM and additional types may be specified. The breakdown entity also points to the starting elements in the breakdown. (Usually for a breakdown with a single root there will only be one starting element.) Thereafter additional levels of breakdown are specified by the use of element_relationship entities. Both the EXPRESS-G and an instance are illustrated below.

standard_ breakdown_type

breakdown	form	breakdown
_type		breakdown
_type

non_standard_ breakdown

includes S[1:?]

element_	definition
element_	definition	element
definition		element
definition

		1
form	root
	root
element_
type	element_group	lsa_element
	element_group	lsa_element

standard_ non_standard_ element_type element_type

Figure 5.5 EXPRESS-G of Breakdown

The breakdown entity has an attribute called “form” which is used to state the form of logic which has been applied in creating the breakdown. Several standard values are provided for this as well as the opportunity to define “non-standard” forms of breakdown. The standard forms are catalogue, functional, hybrid, physical, system, and zone.

This indicates the criteria used by the logistics engineer in specifying the elements in the breakdown. Note that hybrid form implies a combined physical/functional breakdown and should not be used for other combinations.

Each element in the breakdown has an identifier. This is the position in the NPDM which can be used to hold the LCN. There is a separate element_definition entity referenced from the element entity. This allows the use of a common definition (without duplication) for two elements in different breakdowns. Thus, a common set of element definitions can be consistently applied to several breakdowns within a single system or across multiple systems. This corresponds to the use of standardized logistics terms by a particular armed service or other organization. Perhaps somewhat confusingly, each element definition also has an optional form attribute. This is necessary when hybrid breakdowns are defined and enables the nature of a given element in the breakdown to be determined (i.e. is it functional or physical).

The standard values for this attribute is:

−physical: the element represents a level in a physical breakdown or a physical part in a hybrid breakdown;

−functional: the element represents a level in a functional breakdown or a function in a hybrid breakdown;

−zonal: the element represents a zone in a zonal breakdown;

−catalogue: the element represents a level in a catalogue breakdown;

−system: the element represents a level in a system breakdown;

−group: the element is an element_group (see below).

There are two specific subtypes of element. These are:

∙element_group - used to define an element in a breakdown which acts as a collection point for more elements. This is used to deal with the logical form of figures in parts catalogues where the drawing is effectively used to define a group of parts.

∙lsa_element - this carries the additional information as to whether or not an element is to be treated as a candidate for Logistic Support Analysis.

The links between elements are captured using the element_relationship entity. This is also true of the links between levels of indentation in the traditional LCN numbering scheme. Thus for the following LCN breakdown:

Name

28 Fuel system

2801 Fuel storage system

2802 Fuel pressurisation

There will be an explicit element relationship between the element with id 28 and that with id 2801. (Note it is also permissible to make the id of the fuel storage system element 01. The fact that the fuel storage system is a part of the fuel system is captured by the explicit relationship and so there is no longer a need to repeat the “28” in the id of the fuel storage system element.).

There are several types of element_relationship defined in the NPDM. These are necessary to capture all the different links established in the breakdowns currently used for logistics, in the MIL-STD-1388 LSAR or in breakdowns established for catalogues and manuals.

The following types of element relationship are allowed:

−alternate_element_relationship: two elements at the same level of breakdown are alternates to each other;

−element_equivalence_relationship: two elements are equivalents to each other;

−sub_element_relationship: one element is a sub-element of another. (This is the type used to show a new indentation level in the LCN structure.);

−element_conversion_factor: used to specify how values associated with an element are converted to a common basis (such as annual usage);

−element_group_membership: used to show that an element is included in an element group. (This is how to show that a part is included in a figure in a parts catalogue breakdown.);

−element_group_relationship: used to show that two element_group (figures) are related.

5.2.4 Crossing between Breakdowns and Product Design Structure

Not surprisingly, it is extremely useful to be able to cross reference between the breakdown and element structures. It is unlikely to have individual breakdowns for many components (and systems) used in a given large product. Instead there will be elements in the breakdowns that correspond to either components or sub-assemblies. Similarly it is necessary to know which components together provide a certain function in a functional breakdown.

The product_definition_element_relationship entity provides a general link between an element and a product_definition or a product_definition_usage. The reason why it is either a product_definition or a product_definition_usage is that an element (corresponding to an LCN) may refer to either the use of a component (or sub-assembly) that occurs only once, or the use in a particular position of a component (or sub-assembly) that occurs more than once.

4,1 element

related_element

2,2

product_

applies_to

realisation

item

product_design_definition

4,1

realisation_

definition_

realisation_

element

application

element_

select

3,1

relationship

product_definition_usage

element_ realisation

Figure 5.6 EXPRESS-G of crossing between Breakdowns and Product Design Structure

The product_definition_element_relationship entity simply establishes a link. A subtype of product_definition_element_relationship called element_realisation is used to assert that the product_definition is the corresponding product in the case of a physical element (LCN) or provides the function for a functional element (LCN). Note that several product definitions can be realized by the same function (i.e. they all point to the same one). Equally a single sub-assembly may have several functions and so can be linked to several elements in a functional breakdown.

In some cases however, a part may realize a function only in the scope of some overall function. In this case the realisation_application entity can be used to show the function or other types of elements for which the realization is valid.

5.3 EXPRESS G Diagrams

	7,2	7,3	7,1	7,2	7,2
	label	text_select	identifier	label	label
	name	description	id	name	name
	name		id		name
7,3	description classification_	category_type	product_	category	product_	description	7,3
					product_
					category_
text_select	system		category	sub_category	category_		text_select
text_select	system		category	sub_category	relationship		text_select
					relationship

7,4 organization

7,1 identifier

7,2 label

7,3 text_select

7,1 identifier

7,3 text_select

product_

element_

elements S[1:?]

4,1

related_

product_

element

alias_id	: identifier;
assigned_by	: organization;
applied_to	: alias_select;
alias_scope	: OPTIONAL text_select;
END_ENTITY;

alias_id:	The additional identifier.
assigned_by:	The organization which created the alias_id.

			2,1(6)
7,6	1,2		7,2	7,2
scenario	product_version		label	label
applies_to		of_version	name
scenario_			product_context
scenario_	definition
product_	definition	product_definition
definition_		product_definition
definition_
assignment
	7,3	description	id	7,1
	text_select			identifier

			4,2
7,5	realization_of	product_design_	breakdown
product_concept		definition

element_	sub_element_	element_
conversion_	sub_element_	group_
conversion_	relationship	group_
factor	relationship	relationship
factor		relationship

conversion	in_breakdown
*factor	4,2	element_
	4,2	group_variant_
	breakdown	group_variant_
	breakdown	relationship
		relationship
		description	id
REAL		7,3	7,1
		7,3	7,1
		text_select	identifier

		id
element_	element_	role
equivalence_	group_	role
equivalence_	group_
relationship	membership
		indenture

applied_to:	The object to which the alias identifier is applied.
alias_scope:	The optional scope of applicability of the alias_id.

base	: breakdown;
END_ENTITY;
base:	The original element for which an alternate is being specified.

END_ENTITY;
alternate:	A product that may be used in place of the base product.
base:	A product for which another product may be used as an
	alternate.
basis:	A description to specify the rationale and domain of applicability
	of the alternate product.

reference_designator		: OPTIONAL identifier;
END_ENTITY;
reference_designator:	An identifier for the assembly_component_usage in addition to
	the id attribute inherited from the
	product_definition_relationship.

END_ENTITY;
name :	The word or group of words by which the
	assembly_component_usage_substitute is referred to.
description :	The text that characterize the
	assembly_component_usage_substitute.
base :	A product for which another product may be used as substitute.
substitute :	A product that may be used in place of the base product.

form	: breakdown_type;
includes	: SET [1:?] OF element;
END_ENTITY;
form:	An indication of the criteria used to form the breakdown.
includes:	The elements forming the first level of the breakdown.

name	: label;
description : OPTIONAL text_select;
END_ENTITY;
name:	The word or group of words by which the classification system is
	known.
description:	The word or group of words which characterize the
	classification_system

id	: identifier;
definition	: element_definition;
END_ENTITY;
id:	The identification for the element. Can be used to hold either part
	or all of a logistics control number (LCN).
definition:	The definition of the element. Note that several elements from the
	same or different breakdowns can share the same definition.

conversion	: factor;
END_ENTITY;
conversion:	The value to be used in converting occurrence rates between the
	related element and the relating element.

element	: element_definition;
applies_in	: scenario;
END_ENTITY;
element:	The element definition to which the scenario is assigned.
applies_in:	The scenario to which the element_definition applies.

logic	: text_select;
END_ENTITY;
logic:	The logic being used to assert that two elements are equivalent.

root	: OPTIONAL	element;
description : OPTIONAL		text_select;
END_ENTITY;
root:	An element to which the element group as a whole corresponds.
description:	A description of the element group.

END_ENTITY;
id:	The identifier associated with the member element in the element
	group.
role:	The role being played by the element within the group.
indenture:	An indication of the indenture level of the element within the
	figure structure.
quantity:	The quantity of the element included as a member of the element
	group.

relating	: element_group_membership;
related	: element_group_membership;
END_ENTITY;
relating:	The first element group membership being associated.
related:	The other element group relationship being related. If one
	element of the relationship is dependent upon the other, this
	attribute shall be the dependent one.

id:	The identification of the variant.
description:	A description of the variant.

elements	: SET [1:?] OF element;
END_ENTITY;
elements:	The elements to which the product category is related

relating	: element;
related	: element;
END_ENTITY;
relating:	The first or parent element.
related:	The second or child element.

candidate	: candidate_choice;
END_ENTITY;
candidate:	The suffix which indicates what type of candidate item the
	element is (e.g. FULL, PARTIAL etc.).

END_ENTITY;
id:	The identification of the non standard breakdown.
description:	A description of the form of the breakdown and the logic used in
	its construction.
purpose:	A description of the intended purpose of the breakdown.

END_ENTITY;
id:	The identification of the non-standard element type.
description:	The word or group of words that characterize the
	non_standard_element_type.
purpose:	A description of the intended purpose of the
	non_standard_element_type.

ategory));
id	: identifier;
name	: label;
category_type	: OPTIONAL classification_system;
description	: OPTIONAL text_select;

END_ENTITY;
id:	The string that identifies the product_category.
name:	The word or group of words by which the product category is
	referred to.
category_type:	The classification system used to define the product_category.
description:	Optional text that relates the nature of the product category.

END_ENTITY;
id:	The identification of the product definition.
name:	The word or group of words by which the product definition is
	referred to.
description:	Text that relates the nature of the product definition.
of_version:	The product_version to which the product_definition applies.
product_context:	The context for which this product_definition is valid. This may
	include reference to lifecycle stage and engineering discipline
	that created the definition.

id	: identifier;
item	: realisation_select;
related_element	: element;
description	: text_select;

END_ENTITY;
id:	The identifier of the product_definition_element_relationship.
item:	The product or product_usage to which the element is related..
related_element:	The element which is related to the product_definition.
description:	Text that relates the nature of the relationship.