single user login/ shared registration with different domain names?

[snoopy5]

Hi

Currently I use the single user login for PP, RP and classifieds. All are installed on the same server, each on a different subdomain. But the main domain is the same. It works without any problems.

Now I am thinking about the same single user login with more installations which I have. But these other installations use each a different domain (not a subdomain).

Will this single user login still work, if each installation (PP, RP and CL) is on a totally different domainname?

(All domains are on the same server by the way)

Thanks in advance