On 3/6/12 4:19 PM, Randall Gellens wrote: > At 3:30 PM -0700 3/6/12, Peter Saint-Andre wrote: > >> In my working copy I've changed that paragraph to: >> >> Implementations of application protocols MUST NOT programatically >> discriminate between "standard" and "non-standard" parameters based >> solely on the names of such parameters (i.e., based solely on >> whether the name begins with 'x-' or a similar string of characters). > > I like this wording, especially because it more clearly gets at the > heart of the document, which is to not discriminate based only on the > name prefix. > > One question, though: should this be "SHOULD NOT" rather than "MUST > NOT"? The interoperability doesn't depend on implementations > refraining from doing so, rather, we consider it more problematic to do > so than not, so we are making a strong recommendation to not to so. > Hence, "SHOULD NOT". Hi Randall, My co-author Mark Nottingham feels even more strongly about this issue than I do, so I will let him comment. However, note the existence of things like the "x-gzip" and "gzip" content codings in HTTP, which RFC 2068 says are equivalent. An implementation that programmatically discriminated between "standard" and "non-standard" parameters based solely on the parameter names might automatically reject entities for which a content-coding of "x-gzip" is specified, but automatically accept entities for which a content-coding of "gzip" is specified. IMHO that's just wrong, and MUST NOT is appropriate. Peter -- Peter Saint-Andre https://stpeter.im/ _______________________________________________ Ietf mailing list Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf