Storing properties

Hi !

I'd like to know how does a webdav server to store file properties.
I undestrand that you put a/some propertie(s) with a PROPPATCH, and you get them with a PROPFIND, but WHERE are these properties on the server ?
I'm actually working with an Apache server (withe mod_dav module), and I don't understand how does that works...

Thanx in advance.