Subject: [dispatch] draft-yu-tel-dai-07

From: "Ian Elz" <[email-masked]>
Date: Mon, 10 Aug 2009 14:56:53 +0200

James, David, Flemming,

[I have copied this to the dispatch list for further comments. The iptel
wg for which this draft was originally written has been closed.]

We have been looking at the definition of the parameter values defined
in your draft:

         dai        = ";dai="  dai_value
         dai-value  = "no-ind"           /
                      "presub"           /
                      "presub-da"        /
                      "presub-daUnkwn"   /
                      "da"               /
                      "CIC-chrgPty"      /
                      "altCIC-chrgPty"   /
                      "verbal-clgPty"    /
                      "verbal-chrgPty"   /
                      "emergency"        /
                      "presubUnkwn-da"   /
                      "operator"         /
                      pvalue

We are concerned that you have specified mixed case in the values.

The issues arise from the requirements for comparison on tel (RFC 3966)
and sip (RFC3261).

	RFC 3966 states: "URI comparisons are case-insensitive" and goes
on to state "All parameter names and values SHOULD use lower-case
characters, as tel URIs may be used within contexts where comparisons
are case sensitive."

	RFC 3261 states: "Comparison of the userinfo of SIP and SIPS
URIs is case-sensitive. This includes userinfo containing passwords or
formatted as telephone-subscribers. Comparison of all other components
of the URI is case-insensitive unless explicitly defined otherwise.

I would suggest that you align your dai-values with the recommendation
in RFC 3966 to make all the values lower case. If there is a specific
requirement to make these values mixed case then you should specify that
them as being case sensitive in the draft.

Unfortunately we are stuck with the wider issue that tel parameters are
case insensitive when comparing tel URIs but are case sensitive if the
tel URI has been converted to sip URI before the comparison.

Ian Elz

System Manager
DUCI LDC UK
(Lucid Duck)

Office: + 44 118 9024948
[email-masked]