More information about SMIL
"Although MPEG (Moving Picture Experts Group) also looks at content and coding, SMIL is more web-centric unlike MPEG, which is more media centric and involves more than just content and coding. A close comparison would be D-HTML (dynamic hypertext markup language). However, D-HTML uses scripted definitions of local behaviours, without a notion of the presentation's context. Actions such as timed events are therefore difficult to co-ordinate.
Then there are W3C technologies such as cascading style sheets (CSS) which are compatible with SMIL, which
