This clause defines conformance profiles used to characterise MBS Distribution Sessions. MBS Distribution Sessions are characterized by features that are required for the consumption of the MBS Distribution Session. An MBS Client needs to support all features of the MBS Distribution Session in order to consume the MBS Distribution Session. Conformance profiles are defined to enable interoperability and the signalling of the use of features. A conformance profile imposes a set of specific restrictions:

• It may constrain features of the MBS Distribution Session, i.e. the Distribution Method in use.
• It may constrain the content delivered within the MBS Distribution Session, such as the media content types, media format(s), codec(s), and protection formats.
• It may constrain quantitative parameters, such as bit rate.

Conformance profiles defined in the present document constrain features specified in the present document. Externally defined conformance profiles may additionally impose restrictions on other aspects.

A conformance profile is uniquely identified by a fully-qualified term identifier URI from a controlled vocabulary. The term identifiers in the controlled vocabulary shall conform to either the pro-simple or pro-fancy productions specified in Section 4.5 of RFC 6381, without the enclosing DQUOTE characters, i.e. only the unencodedv or encodedv productions respectively.

• Profile identifiers defined in the present document shall be URNs conforming to RFC 8141. A controlled vocabulary of conformance profiles defined in the present document is specified in clause C.2.
• Externally defined conformance profiles may use profile identifiers that are URNs conforming to RFC 8141 or URLs conforming to RFC 3986.
• When a URL is used, it should also contain a date specifier in the form YYYY-MM. The assignment of the URL shall be authorized by the owner of the domain name in the authority part of the URL on or very close to that date, to avoid problems when domain names change ownership.

The conformanceProfiles property as defined in clause 5.2.4 indicates a list of profiles to which an MBS Distribution Session conforms. The MBS Distribution Session shall conform to every profile listed. An MBS Client conforming to any of the listed profiles is permitted to access and process the MBS Distribution Session and shall process the MBS Distribution Session according to the client requirements defined by its chosen conformance profile. MBS Distribution Sessions conforming to the Baseline MBS Distribution Session Profile defined in clause 12.4 may omit the conformanceProfiles property.

The Baseline MBS Distribution Session Profile characterises MBS Distribution Sessions as specified in the present document. For MBS Distribution Sessions conforming to the Baseline MBS Distribution Session Profile, the following applies:

• If the User Service Description indicates the Object Distribution Method, then the MBS Distribution Session shall conform to the requirements in clause 6.
• If the User Service Description indicates the Packet Distribution Method, then the MBS Distribution Session shall conform to the requirements in clause 7.

An MBS Client conforming to this profile shall support the MBS Client requirements for the Object Distribution Method as defined in clause 6 and the MBS Client requirements for the Packet Distribution Method as defined in clause 7. The Baseline MBS Distribution Session Profile is identified by the URI urn:3GPP:26517:17:baseline as specified in Annex C.2.