Subject: An SDP ABNF problem ? (RFC 2327)

From: [email-masked]
Date: Mon, 12 Feb 2001 18:37:42 +0530

Hi,
Just wanted to confirm if this is a bug:

In page 19 of RFC 2327, you write:

"  Attributes that will be commonly used can be registered with IANA
   (see Appendix B).  Unregistered attributes should begin with "X-" to
   prevent inadvertent collision with registered attributes.  In either
   case, if an attribute is received that is not understood, it should
   simply be ignored by the receiver."

However, the grammar for the attribute line (a=) in Appendix A lists :

attribute-fields =    *("a=" attribute CRLF)
attribute =           (att-field ":" att-value) | att-field
att-field =           1*(alpha-numeric)
alpha-numeric =       ALPHA | DIGIT

Hence there is no provision for the hyphen "-" character in the field.

So I cannot put in a "X-mynwattr".

could you please clarify ?

regds
Arjun
--
Arjun Roychowdhury @ Hughes Software Systems

---

From: Mark Handley <[email-masked]>
Date: Mon, 12 Feb 2001 08:46:47 -0800

>could you please clarify ?

Thanks for letting us know.

The BNF is incorrect.  In general, RFC 2327 has a number of errors in
the BNF - when the BNF contradicts the text, our policy has been that
the text is correct.

This will be corrected before SDP goes to Draft Standard.

Cheers,
	Mark