26.1413GPPIP Multimedia System (IMS) Messaging and PresenceMedia formats and codecsRelease 17TS
The 3GPP IMS Messaging and Presence uses a subset of SMIL 2.0  for media synchronisation and scene description. IMS clients and servers with support for media synchronization and scene descriptions shall support the 3GPP SMIL Language Profile defined in .
– This profile is a subset of the SMIL 2.0 Language Profile but a superset of the SMIL 2.0 Basic Language Profile. Document  also includes an informative annex A that provides guidelines for SMIL content authors.
Additionally, XHTML Mobile Profile  for scene description should be supported. IMS clients and servers with support for scene descriptions based on XHTML shall support XHTML Mobile Profile , defined by the WAP Forum.
– XHTML Mobile Profile is a subset of XHTML 1.1 but a superset of XHTML Basic.
Annex A (informative):