Try using the same technique that we worked through previously with a Yahoo! OpenID—for example,
https://me.yahoo.com/pmularien. You will find that it doesn't work, as it did with the other OpenID providers. This illustrates a key problem with the structure of OpenID, and highlights the importance of OpenID-enabled user registration.
The actual OpenID that Yahoo! returns will be similar to the following:
https://me.yahoo.com/pmularien#9a466. In OpenID terminology, the identifier that the user enters in the login box is known as the user-supplied identifier. This identifier may not actually correspond to the identifier that uniquely identifies the user (the user's claimed identifier ...