SP ACS extra query string parameter rejected by IdPv3, not rejected by IdPv2

[Tom Scavo]

On Sat, Mar 12, 2016 at 12:17 PM, Waldbieser, Carl
<waldbiec at lafayette.edu> wrote:
>
> Which behavior is correct?  IdPv2 being tolerant of the extra parameter, or IdPv3 rejecting it?

I would say the latter. AFAIK, SAML software typically does a strict
string match against what's in metadata. My guess is that V2 is
ignoring the query string altogether. The SAML spec appears to be
silent regarding this question.

Tom