Scheme of attributes?

[Alessio Pace <billy corgan tiscali it>]

Hi, I am really new to Beagle and I am studying personal document
managament technologies as my CS thesis.

I read the beagle wiki and I have some questions:

1) are the attributes (metadatas) of the documents system wide
("author=..") and/or personal for the users ("interest=high") ? 

2) is there a global naming scheme for those attributes, such that every
application developer could code knowing a priori that he can query in
the index for an "MP3 Document" that has such attributes, and also
others more general attributes because being an mp3 it is also a
specification of a "Multimedia Document" ?

3) is the ranking for the searches based "only" on a boolean match or is
there a more subtle ranking algorithm ?

I think it is enough now :)

Thanks
Alessio Pace.