How is Binding Edge Determined?

I noticed that text-align defines "outside" and "inside" in terms of the 
  "binding edge". However, I couldn't find any reference to "binding" or 
"bound" or "bind" outside of the discussion of text-align. Thus my 
question: how is the binding edge defined or determined? That is, I 
might have a normally oriented page (before is top) that is top-bound or 
I might, for some bizare reason, bind a left-to-right document on the right.

Have I missed something?

Thanks,

Eliot
-- 
W. Eliot Kimber, eliot@isogen.com
Consultant, ISOGEN International

1016 La Posada Dr., Suite 240
Austin, TX  78752 Phone: 512.656.4139