Subject: [Sip] Duplicate parameter names

From: "Dale Worley" <[email-masked]>
Date: Thu, 01 Jan 2009 14:05:23 -0500

I know that this question has been wrangled over, but I'm having trouble
determining the proper resolution.

A SIP name-addr has three types of parameter:  URI-parameters, headers,
and header-parameters:

	<sip:[email-masked];name=value>
	<sip:[email-masked]?Name=value>
	<sip:[email-masked]>;name=value

Which of these admit two parameters with the same name?

RFC 3261 section 19.1.1 clearly specifies that URI-parameters may not be
duplicated.

RFC 3261 section 7.3.1 implies that headers can be duplicated, because
in SIP requests some headers can appear more than once even though they
cannot be combined into a comma-separated list.

But what about the header-parameters?  I can't find any clear statement
in RFC 3261.  But I'm sure we've discussed this and come to a
conclusion...

Dale

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From: Paul Kyzivat <[email-masked]>
Date: Thu, 01 Jan 2009 19:02:51 -0500

> in RFC 3261.  But I'm sure we've discussed this and come to a

Section 7.3.1 of 3261:

    Many existing header fields will adhere to the general form of a
    value followed by a semi-colon separated sequence of parameter-name,
    parameter-value pairs:

          field-name: field-value *(;parameter-name=parameter-value)

    Even though an arbitrary number of parameter pairs may be attached to
    a header field value, any given parameter-name MUST NOT appear more
    than once.

	Thanks,
	Paul

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From: "Dale Worley" <[email-masked]>
Date: Fri, 02 Jan 2009 11:38:21 -0500

>     a header field value, any given parameter-name MUST NOT appear more

Thanks!  I was wondering why I didn't find it when searching 3261, and
it seems to be because the word "parameter" isn't preceded by "header"
or "field" anywhere in that passage.

Dale