Gary, Two things.... 1. I included the wrong text in the mail I originally sent you... The text should have been:- "To include multiple elements of nonStandardData in an H.225 message the nonStandardParameter is used in the following way. This special use of the nonStandardParameter is identified by setting the nonStandardIdentifier to be an OBJECT IDENTIFIER of type {itu-t (0) recommendation (0) h (8) 2250}. In this case the information contained in the data part of the nonStandardParameter consists of a fragment of ASN.1 encoded into an OCTET STRING (The ASN.1 encoding rules are the same as those for all H.225 messages). The ASN.1 fragment has the following syntax: ExtendNonStandard ::= SEQUENCE OF NonStandardParameter It is recommended that entities use this method for including nonStandardData in messages even if they only insert one piece of information as it allows other entities in the signalling path to either add or delete their own nonStandardData without overwriting information inserted by the originating entity. If intermediate entities on the signalling path need to insert nonStandardData when there is already nonStandardData present that is not of the extended form described above they are encouraged to take measures to ensure that the original nonStandardData can be recovered by entities further down the signalling path once those entities have removed any nonStandardData specific to them. This can be achieved by nesting the original nonStandardData field inside the nonStandardParameter created by the intermediate entity. However, endpoints should be aware that if they do not insert nonStandardData in the extended form it may be overwritten by intermediate signalling entities." This is less enforcing than the text you received before, which seems more in line with backwards compatibility. 2. If you're imply that it should be in H.225.0 I think that makes sense (even though I had originally assumed it would go in H.323). In the discussion on nonStandardParameter in Section 7.6 H.225.0 seems a good place. Regards, Pete ================================= Pete Cordell BT Labs E-Mail: pete.cordell@bt-sys.bt.co.uk Tel: +44 1473 646436 Fax: +44 1473 645499 =================================
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Pete Cordell