[Users] uuid-based setup

Hi again, Just another question: If I'd like to switch from a username/domain-based setup to an uuid-based setup, what exactly would I have to consider? As far as I have found in the docs (or better: what I assume from what I've found in the docs), I'd have to load the uuid from subscriber like avp_db_query("select uuid from subscriber where username='$au' and domain='$ar'", "$avp(i:500)"); And then I can use i:500 as uuid for loading other avps? Or is there an implicit way to get the uuid, e.g. during www/proxy_authorize? I think I have some troubles to get the link between username/domain and uuid... Thanks, Andy