This section is informative.
A zip archive of the SMIL 3.0 Relax NG Schemas is available for user convenience allowing validation of SMIL 3.0 documents.
These SMIL 3.0 Relax NG Schemas are currently only a translation of the SMIL 3.0 DTD. They are not yet enriched whith the capabilities that Relax NG Schemas offer over DTDs. The SYMM WG will do its best to maintain and enrich these SMIL 3.0 Relax NG Schemas.