MUST, SHOULD, and MAY, some key words from RFC 2119

["Ogden, Jeff" <jogden@ptc.com>]

Included below are some words taken from RFC 2119 on “Key words for use in RFCs to Indicate Requirement Levels". I think we are going to need to use this or a similar approach in the DITA standard.

1. MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the

   definition is an absolute requirement of the specification.

2. MUST NOT   This phrase, or the phrase "SHALL NOT", mean that the

   definition is an absolute prohibition of the specification.

3. 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.

4. 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.

5. 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.)

To see the full RFC (its short), see:  http://www.ietf.org/rfc/rfc2119.txt?number=2119

Note that as we split the DITA Specification into multiple specifications, that an entire specification may be REQUIRED, RECOMMENDED, or OPTIONAL, but within the individual specifications there will be items that are REQUIRED, RECOMMENDED or which are OPTIONAL.

So, if I take the summary from Michael’s recent note:

-          everyone needs to support the core; 

-          specialized support (beyond core defaults) for the specialized parts of the spec are optional but encouraged, and should represent an established user community;

-          specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations are up to the user or their partners to provide

I can rewrite it using the RFC terms as follows:

-          everyone MUST support the core; 

-          specialized support (beyond core defaults) for the specialized parts of the spec are RECOMMENDED, and MUST represent an established user community;

-          specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations is OPTIONAL and up to the user or their partners to provide.

Michael, how did I do?

 -Jeff