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Glossary |
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- MAY
- From rfc2119: 'This word, or the adjective "OPTIONAL", mean that an item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because the vendor feels that it enhances the product while another vendor may omit the same item. An implementation which does not include a particular option MUST be prepared to interoperate with another implementation which does include the option, though perhaps with reduced functionality. In the same vein an implementation which does include a particular option MUST be prepared to interoperate with another implementation which does not include the option (except, of course, for the feature the option provides.)'
- MUST
- From rfc2119: 'This word, or the terms "REQUIRED" or "SHALL", mean that the definition is an absolute requirement of the specification.'
- MUST NOT
- From rfc2119: 'This phrase, or the phrase "SHALL NOT", mean that the definition is an absolute prohibition of the specification.'
- OPTIONAL
- See MAY.
- RECOMMENDATION
- A conformace criteria where the imperative is SHOULD, SHOULD NOT, or RECOMMENDED.
- RECOMMENDED
- See SHOULD.
- REQUIRED
- See MUST.
- RULE
- A conformace criteria where the imperative is MUST, MUST NOT, SHALL, SHALL NOT, or REQUIRED.
- SHALL
- See MUST.
- SHALL NOT
- See MUST NOT.
- SHOULD
- From rfc2119: 'This word, or the adjective "RECOMMENDED", mean that there may exist valid reasons in particular circumstances to ignore a particular item, but the full implications must be understood and carefully weighed before choosing a different course.'
- SHOULD NOT
- From rfc2119: 'This
phrase
, or the phrase "NOT RECOMMENDED"mean that there may exist valid reasons in particular circumstances when the particular behavior is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behavior described with this label.'
We struck out ', or the phrase "NOT RECOMMENDED" ' above 1) "NOT RECOMMENDED" is not otherwise defined or mentioned in rfc2119, and 2) In normal English usage, the phrase "NOT RECOMMENDED" would mean something quite different: a lack of a recommentation. Because of this confusion, this phrase SHOULD be avoided in specs that make reference to rfc2119 or use its conventions.
Unless stated otherwise, all text on this page which is either unattributed or by Mark S. Miller is hereby placed in the public domain.
