Subject: [MMUSIC] [mmusic] #20 (rfc4566bis): 4566bis: Lack of a consistent format for defining new attributes.

From: "mmusic issue tracker" <[email-masked]>
Date: Wed, 09 Jul 2014 12:57:57 -0000

#20: 4566bis: Lack of a consistent format for defining new attributes.

 Paul K.: Many people look to 4566 for examples of how to do this, but it
 provides bad examples. IMO 4566bis should show the definition of all
 attributes in a style that complies with a recommended format for defining
 attributes. (Of course that implies that we could agree on such a format.)

 From http://www.ietf.org/mail-archive/web/mmusic/current/msg13471.html

 One question is whether the definition of a new attribute should:
 1) define the full syntax of the line (starting with "a="),
 2) should provide additional definitions of <attribute> (via "/=")
 3) should provide additional definitions of <att-field> and <att-value>
   (via "/=")
 4) provide definitions of the name and value that are consistent with
   <att-field> and <att-value> without formally extending the
   definitions of those.

 Note that 4566 loosely follows (4) but gives the definitions informally
 rather than via ABNF. So it gives no guidance on how to use ABNF for this.
 A number of drafts have chosen to follow (2). Some have started to do (1)
 but I don't know of any that ended up that way.

 A question I have raised is: if (2) or (3) is followed, does that mean
 that the draft doing so must be considered as "updating" 4566?

 One thing that people sometimes forget when defining new attributes is
 that the syntax of the new attribute MUST also be valid when parsed by the
 "generic" attribute syntax. AFAIK there is no way in ABNF to specify that.
 I think that (4) comes closest.

-- 
-------------------------+-------------------------------------------------
Reporter:                |      Owner:  draft-ietf-mmusic-
  [email-masked]       |  [email-masked]
    Type:  enhancement   |     Status:  new
Priority:  major         |  Component:  rfc4566bis
 Version:                |   Severity:  Active WG Document
Keywords:                |
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Ticket URL: <http://trac.tools.ietf.org/wg/mmusic/trac/ticket/20>
mmusic <http://tools.ietf.org/mmusic/>

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From: "mmusic issue tracker" <[email-masked]>
Date: Wed, 09 Jul 2014 13:01:02 -0000

Changes (by [email-masked]):

 * owner:  [email-masked] => [email-masked]

-- 
-------------------------------+--------------------------------
  Reporter:  [email-masked]  |      Owner:  [email-masked]
      Type:  enhancement       |     Status:  new
  Priority:  major             |  Component:  rfc4566bis
   Version:                    |   Severity:  Active WG Document
Resolution:                    |   Keywords:
-------------------------------+--------------------------------

Ticket URL: <http://trac.tools.ietf.org/wg/mmusic/trac/ticket/20#comment:1>
mmusic <http://tools.ietf.org/mmusic/>

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From: Flemming Andreasen <[email-masked]>
Date: Fri, 18 Jul 2014 17:34:44 -0400

I think I agree with 4), but the important part here is that we actually 
get a valid ABNF for all extensions.

-- Flemming