Integrating SMIL Timing into Other XML-Based Languages

This segment of the working draft specifies an architecture for applying timing information to XML documents. It specifies the syntax and semantics of the constructs that provide timing information. This approach builds on SMIL by preserving SMIL's timing model and maintaining the semantics of SMIL constructs.

http://www.w3.org/TR/2000/WD-smil-boston-20000225/Time-Integrate.html