PMH has an operation listMetadataFormats which lists the local names and
any other information it has about the formats it supports.

eg:
http://alcme.oclc.org/openurl/servlet/OAIHandler?verb=ListMetadataFormats

(view source to see the response without the helpful XSLT)

Eg, they have the problem, but don't even bother with a registry.

Rob


On Wed, 2009-05-20 at 15:30 +0100, Ray Denenberg, Library of Congress
wrote:
> From: "Dr R. Sanderson" <[log in to unmask]>
> > There isn't one, but the protocol has the same requirements as SRU and
> > OpenURL.
>
> I remain confused. If the protocol has the requirement to specify a schema
> identifier, there must be some way for an implementor to (1) find out the
> appropriate identifier for a particular schema, including finding out that
> there isn't one; and (2) register an identifier for a schema when there
> isn't one.
>
> --Ray