packet length: this field, coded as an unsigned integer in the range 1 to 255, indicates the length in bytes of the data field of each packet (the total packet length is three bytes longer as it includes the header and CRC fields).

NOTE: All packets contained in one data stream have the same length (see clause 6.6.4).

6.4.3.16Extension data entity - type 15

6.4.3.16.0General

To permit additional data entities to be defined, data entity type 15 is used. The first four bits of the body of the data entity contain the data entity Extension type field.

6.4.3.16.1Service linking information data entity - type 15, extension 0

Service linking information can be used to link together services carrying exactly the same content (hard link) or carrying related content (soft link). This data entity uses the list mechanism for the version flag.

The information is as follows:

The following definitions apply:

Extension type: this 4-bit field shall be set to 0000 to indicate the correct extension for service linking information.

Id (Identifier) list flag: this 1-bit flag shall indicate whether the n Ids, together with the preceding byte, is present or not, as follows:

0:Rfu, IdLQ, Data flag, Number of Ids, and n Ids absent;

1:Rfu, IdLQ, Data flag, Number of Ids, and n Ids present.

LA (Linkage Actuator): this 1-bit flag shall indicate whether the link is active or inactive (potential), as follows:

0:potential future link or de-activated link;

1:active link.

S/H (Soft/Hard): this 1-bit flag shall indicate whether the link is soft or hard, as follows:

0:Soft link (related services);

1:Hard link (services carrying the same content).

ETSI

ILS indicator: this 1-bit flag shall indicate whether the link affects only one country (national) or several countries (international), as follows:

0:national link;

1:international link (or DRM or AMSS).

Linkage sets which include services broadcast using DRM or AMSS shall always be an international link, even if all linked services are intended for national use.

NOTE: It is possible but not recommended to signal linkage sets that do not include DRM services.

LSN (Linkage Set Number): this 12-bit field represents a number which shall be common to all Services linked together as a set. The use of LSN = "0000 0000 0000" is reserved.

For an international link, the LSN shall be structured according to IEC 62106 [13].

Rfu: this 1-bit field shall be reserved for future use of the IdLQ, the Rfa, the Number of Ids and the Id list fields. The Rfu bit shall be set to zero for the currently specified definition of the associated fields.

IdLQ (Identifier List Qualifier): this 2-bit field shall indicate how the identifiers, contained in the Id list, are qualified, as follows:

b6 - b5

0 0 : each Id represents a DAB service (see ETSI EN 300 401 [3]);

01 : each Id represents an RDS service (see IEC 62106 [13]);

10 : not used;

1 1 : each Id represents a DRM or AMSS Service (see ETSI TS 102 386 [14]).

Data flag: this 1-bit field is shall indicate whether each Id corresponds to a DAB data service or not, as follows:

0:each Id does not correspond to a DAB data service;

1:each Id corresponds to a DAB data service.

Number of Ids: this 4-bit field, expressed as an unsigned binary number, shall specify the number of identifiers in the Id list (maximum 15).

n Ids: this field carries n service identifiers (n in the range 1 to 15). The bit length and information for every Id value depends upon the value of the IdLQ, ILS indicator and Data flag fields as follows:

Table 22b

The operational use of this data entity is identical to that of the DAB FIG 0/6, see ETSI TS 103 176 [15].

6.4.3.16.2Other data entity type 15 extensions

Other data entity type 15 extensions are reserved for future definition.

ETSI