After reviewing the spec, it appears that it's left up to the implementer to figure out how to actually use this. If a keyRef is a "checked" tModel, then the UDDI server (on publish event) could then call the Validation API. It is described as an external service from the UDDI server.
Task A, define a way for a user to create a checked tModel and someone reference a binding Template that points to an implementation of VS API.
Task B, add methods to the jUDDI API endpoint that would enable someone to define the list of valid values for a given tModel. I.E. set_ValidValues. We can then provide our own implementation.