"The importance of SMIL 3.0 is that it contains a set of user-requested features that provide exciting new functionality, while retaining all the advantages of a declarative (that is, without scripting) approach to building a multimedia presentation," said Dick Bulterman, chair of the Synchronized Multimedia Working Group, which published the specification.
The new features in SMIL (pronounced, "smile") are a direct response to user and industry demand. For instance, the standard allows full-motion, timed captions and labels to be directly inserted in the presentation (called smilText). And SMIL's media pan-zoom control allows people to create "Ken Burns"-style animations easily for photos and visual content. SMIL 3.0 also allows authors to embed timed metadata in presentations, making SMIL a useful descriptive language for the development of Semantic Web resources that evolve over time.
Personal Note: SMIL's Content Control Modules allow for selective/adaptive multimedia presentations through the switch element. SMIL 3.0 Content Control introduces three new attributes: allowReorder, systemBaseProfile, and systemVersion. Additionally, the new module RequiredContentControl has been defined that allows the systemRequired attribute to be specified in profiles that do not otherwise use SMIL content control.
The profile name might one of
"Language" | "UnifiedMobile" | "Daisy" | "Tiny" | "smilText" |User-defined-profile-name. User-defined profiles are possible also.