WordPress MU

I'm looking for where the roles are set for a user in the database. Is this it: a:2:{s:13:"Administrator";b:1;s:13:"administrator";b:1;}

I see that in the the wp_usermeta under the meta_value column.

So if I want to look for a certain user and get their role in all blogs, I have to parse through that field in the table, or is there something better elsewhere. I pictured something like:
userid, blogid, roleid in some other table, linking them all together.

But is what I found how WPMU sets the roles for users in the database?

Thanks.