The version 1.0 registry data model uses Resource Identifiers in several places to identify which standard a particular resource follows. By using IVOA resource identifiers in this way there is an implicit assumption that the standard is itself registered - though no formal requirement to do so. The VOStandard data model and schema provides a framework in which IVOA standards can be described in the registry.
This work used to be tracked via the RegDMStandards page. That page is now deprecated. (RayPlante - 10 Nov 2009)
The previous version of the schema was distributed as part of the RegUpgradeToV10 page