Here are some more responses from the IETF concerning the RFC2119 key words. It seems some of these words were actually identified in earlier RFCs, particularly 1122 & 1123. RFC1123 also includes the Robustness Principle which I have cited before. Be liberal in what you accept, and conservative in what you send This says to me that we should ignore errors where we can and continue processing which is one of the things I have been arguing for, without much success. If we want true interoperability, we need to follow this principle. Regards, David.