Re: [apps-discuss] Review of draft-ietf-eai-rfc5337bis-dsn-1

["Lyndon Nerenberg (VE6BBM/VE7TFX)" <[e-mail]>]

> So I suggest having a citation for the original version of the rule be included 
> in a comment associated with the new rule.
> 
> For example:
> 
>       generic-address =/ utf-8-enc-addr
>                         ; updates Section 3.2.3 of [RFC3798]

FWIW, this is what I did for IMAP Binary (3516); it doesn't seem to have
caused any confusion:

  7.  Formal Protocol Syntax

   The following syntax specification uses the augmented Backus-Naur
   Form (ABNF) notation as used in [ABNF], and incorporates by reference
   the Core Rules defined in that document.

   This syntax augments the grammar specified in [IMAP4rev1].

   append         =/  "APPEND" SP mailbox [SP flag-list]
                      [SP date-time] SP literal8

   fetch-att      =/  "BINARY" [".PEEK"] section-binary [partial]
                      / "BINARY.SIZE" section-binary

   literal8       =   "~{" number "}" CRLF *OCTET
                      ; <number> represents the number of OCTETs
                      ; in the response string.

   msg-att-static =/  "BINARY" section-binary SP (nstring / literal8)
                      / "BINARY.SIZE" section-binary SP number

   partial        =   "<" number "." nz-number ">"

   resp-text-code =/  "UNKNOWN-CTE"

   section-binary =   "[" [section-part] "]"

The base IMAP RFC (3501) made this construct easy and (I think)
relatively obvious.  YMMV.  If a grammar extension is globally
applicable to a parent specification, I think the subject document
reads easier if the extension is called out at the top of the grammar,
rather than littering each ABNF element with a callout comment.  The
alternatives can get very noisy, especially if there is multiple
inheritance involved.

--lyndon