Gaby itself doesn't know about what it will be used for. It is ready to manage your addresses, your CDs, your tapes and if you ask it gently it could even does your laundry.
You'd say that those jobs are different but there is not a great differences between selecting CDs from Belgian rockers and selecting white but dirty socks.
Well. But where does Gaby know its job ? The answer is (tadam...): in descfiles.
They are simple text files and can thus be created by any text editor floating on your hard disk but there is also a special tool to create them without any need to know about the way to write them (see the appendix).
in case you don't use apt to do it
even if you prefer the former
Descfiles are short for "Description files"