@mwhagedorn I realize it's OpenStack and not HP-specific. What I clearly asked poorly is whether you (HP) allow API consumers to optionally specify a tenant?  As you seem to indicate above, it is an option on the HP API.  In our (Rackspace's) case, we have a 1-to-1 relationship between users and tenants in our API so this doesn't effect us.

I tend to agree with your perspective.  If you don't provide a tenant, you should know that you're looking at all tenants/projects for that user and not a specific one, right?

This is where I'd be inclined to add OSC-specific public methods to auth to a project/tenant or auth without. That is, I don't feel that the presence or absence of a hash arg is such a clear way for the user to indicate intent whereas a well-named method is, perhaps, better.