Problem with resolution of Issue 221

I was about to incorporate the resolution to issue 221[1] when I noticed
an inconsistency:

We say that a sender MUST NOT send a message containing Processing
Instructions. However, for receivers we only say SHOULD detect PIs and
generate a fault.

In the case of an intermediary ( the case we were thinking of when we
said 'SHOULD' for receivers ) this will not work, as the intermediary is
also a sender. Therefore, in order to comply with the MUST it has to
detect PIs in the inbound message, otherwise when it sends the message
onward, it might be violating the MUST.

On balance I think the best we can get away with is SHOULD NOT

Gudge

[1] http:///lists.w3.org/Archives/Public/xmlp-comments/2002Aug/0014.html