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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] iSCSI: requirements terminologyI've seen some confusion over use of words to express requirements in the iSCSI draft. There are a couple of important points to keep in mind: (1) Unless there is some clear reason in the text of the iSCSI draft to interpret them in some other fashion, "prohibited" is equivalent to "MUST NOT" and "mandatory" is equivalent to "MUST" (in their RFC 2119 meaning in both cases). While RFC 2119 terms provide clarity in requirement statements, the IETF does not require that all requirements be expressed using RFC 2119 terms, and it would certainly be wrong to interpret "prohibited" and "mandatory" as not stating requirements solely because those two terms are not defined in RFC 2119. (2) OTOH, use of an RFC 2119-defined term in lower case (e.g., "must", "should") assigns the common usage (i.e., dictionary) meaning to that term rather than its RFC 2119 meaning. Such a term may still express a requirement, but that depends on the specific usage and context. It is also the case that the common usage meaning of "should" is weaker than the RFC 2119 meaning of "SHOULD" (and similarly for "should not" vs. "SHOULD NOT"). It is generally reasonable to initially assume that use of a lower case version of an RFC 2119 term was a deliberate decision made by the draft author(s) and/or the WG to limit usage of RFC 2119 terms in accordance with the guidance in Section 6 of RFC 2119, but this needs to be checked based on the actual usage and context in each case. Thanks, --David ---------------------------------------------------- David L. Black, Senior Technologist EMC Corporation, 176 South St., Hopkinton, MA 01748 +1 (508) 293-7953 **NEW** FAX: +1 (508) 293-7786 black_david@emc.com Mobile: +1 (978) 394-7754 ----------------------------------------------------
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