As I understand it, GEMM is a database covering CD's...something like the Abrams files are to 78's. Thus, if you have your collection of sounds (either as recordings or as computer files) catalogued in digital form, you could then add the data to an ultimate collection of data on every digital sound recording that has ever existed (#3).
There are at least two versions of the database you describe, but GEMM is Global Electronic Music Marketplace -- similar to alibris.com and abebooks.com for books. It's a clearing house for small dealers...and a wonderful place to find things. I've been using it for at least six years.