URI binding query parameter: rationale?

My colleague Hubert Le Van Gong tried to send this question to the  
SSTC list, but it doesn't seem to have gone through, even though he's  
on the list.  Here's a re-send (since I couldn't recall the rationale  
for this myself!):

> Hi there,
>
> [in section 3.7.5.1 of the  bindings spec.]
> Could someone please explain the rationale behind forcing the format  
> of the URI
> that points to a SAML assertion in the SAML URI binding (i.e. a  
> unique query string
> parameter of the form ID=xxxx)?
>
> Why not leaving the format of this URI to the implementor?

	Eve

Eve Maler                                         +1 425 947 4522
Principal Engineer                            eve.maler @ sun.com
Business Alliances group                    Sun Microsystems, Inc.