I'm referring to the code that appears automatically on the RegisterExternalLogin.aspx and code behind pages.
Presumably the returned username from FB or wherever is checked against a database table to see if it is already associated with a registered user of my site and if it is found to be associated it will return True and, if not, will return False and the user can then enter their registered user name for my site and then the returned user name from FB will be saved to a table and associated with the registered user of my site.
So what tables are looked at within this process?