Sample Federation URL:
I make this post, as much about a note to myself – as for others. This URL will avoid using the Alias service, and initiate a HTTPPost SAML flow.
Here is some additional notes from the IBM Knowledge Center:
http://www-01.ibm.com/support/knowledgecenter/SSZSXU_6.2.2.6/com.ibm.tivoli.fim.doc_6226/admin/concept/handlingunspecifiednameid.html