> But I'm not sure schemas exist that will actually validate the semantic
> content you want validated.
I'm not sure such a thing would even be desirable.
Even ignoring that there will be plenty of invalid data that you just
have to find a way of dealing with, MARC is hopelessly complex and
needs to be normalized before anything useful can be done with it.
Unless the purpose of the validation is to determine if files supplied
to you meet specifications (e.g. vendor provided files), I would
imagine that validation would cause more problems than it would solve.