The data structure for is not published so there is no written document for it. Components in portal are global, which means they do not fall in the domains/roles and user hierarchy.
A user stores only specific attributes that are customized for him for example, if an firstName is customized for him and that is attribute/value pair stored in his profile, he doesn't have a copy of the whole component in his user profile.
Take a look at the ldif dump, it should give you an ide a ..
I do not think that this information can be made public. However, you can look at the internal LDAP server "cn=iplanetwebtop, dc=youdomain" tree to know the information being stored. However, the profile server code which runs on the internal webserver (at default port 8080) caches the information in the internal LDAP server.