Subject: Appropriate response code if server wants to enforce conditional PUT/DELETE?

From: Jan Algermissen <[email-masked]>
Date: Mon, 29 Jun 2009 07:30:21 -0400

Hi,

(excuses if this is OT. OTH, the question might be relevant to HTTPbis)

is there an/what is the appropriate response code when a server wants  
the client to use an If-Match header on a PUT request but the client  
did not send one?

Thanks,
Jan