They don't want you to know for sure.
Copyright trolls often have no registrations, or faulty registrations.
But, the uncertainty makes some people pay out of fear.
Here's the thread about the corrupted masterfile discs:
http://www.extortionletterinfo.com/forum/getty-images-letter-forum/many-of-masterfile-cd's-with-images-at-us-library-of-congress-are-corrupted/Perhaps, they'd be stored at the library of congress?
http://www.loc.gov/rr/More info from this Wikipedia entry:
http://en.wikipedia.org/wiki/Copyright_CatalogNature of catalog entries and access to copies of documents The Catalog of Copyright Entries, the Copyright Card Catalog, and
the online files are indexes, not reproductions of original documents.
To view or copy the original documents yourself, you must visit the Copyright Office.Information such as registration numbers may be obtained from these files.
Providing this information yourself rather than paying a fee to have the Office search for it will reduce the cost of obtaining records and copies from the Copyright Office.
S.G.