rfc2119
RFC2119
Definitions
- MUST This word, or the terms "REQUIRED" or "SHALL", mean that the definition is an absolute requirement of the specification.
- MUST NOT This phrase, or the phrase "SHALL NOT", mean that the definition is an absolute prohibition of the specification.
- SHOULD 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 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.
- MAY 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.)
On this wiki
Often, microformat specifications (and their drafts) will use the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL". These are to be interpreted as described in RFC2119 and MAY include a link to this page, or directly to the RFC.
Templates
The following templates are available for use on this wiki:
- {{rfc2119-intro}} - see template:rfc2119-intro
- {{must}} = MUST
- {{must-not}} = MUST NOT
- {{required}} = REQUIRED
- {{shall}} = SHALL
- {{shall-not}} = SHALL NOT
- {{should}} = SHOULD
- {{should-not}} = SHOULD NOT
- {{recommended}} = RECOMMENDED
- {{may}} = MAY
- {{optional}} = OPTIONAL
These adhere to the W3C Manual of Style guidelines for RFC2119.
On other web pages
Markup suggestions
When using RFC 2119 terms on your own web pages, consider re-using the mark-up pattern from the W3C Manual of Style (in particular class="RFC2119" - note capitalization), and perhaps their suggested style rule as well.
In addition, see Edward O’Connor POSH suggestion for marking up the commonly used initial paragraph declaring RFC 2119 terms in documents.
Microformat proposal
Some have suggested considering a new microformat for marking up use of RFC 2119 terms.
It appears there is no need for such a new microformat however. Following W3C's established practice, and Edward O'Connor's POSH suggestion for the initial paragraph, appears to be sufficient.