NMTokens in WSDL name attributes

Sorry if this is a dumb question, or has been answered before, but why are the name attributes of most elements in WSDL (e.g. message, part) defined to have the type NMTOKEN, as opposed to NCName, as do most elements in XML schema?

I thought that XML schema made them NCName so that one could reference them via QName from elsewhere, without having to worry about having the colon character to mess things up.  Is this a non-issue for WSDL?  Or maybe it's a non-issue for XML Schema and I'm very confused...

Anyway, any guidance will be greatly appreciated,

Thanks,

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Mark Young
mark@kamiak.com

 p.s.  I'm REALLY sorry if this got sent twice -- I messed up the address the first time.