Limitation of nonStandardData

Douglas Clowes dclowes at OZEMAIL.COM.AU
Mon Dec 1 23:52:03 EST 1997

I had also noted this potential limitation. While the 'SEQUENCE OF' is ther
nicest fix for it, an alternative possibility is to wrap (encapsulate) the
original nonStandardData in the new one (as part of the data) and unwrap it

This would work where the message path is EP-GK-GK-EP and the EP's are
exchanging nonStandardData plus the GK's are also.


At 19:02 1/12/97 -0000, you wrote:
>Dear All,
>I have noticed that there is a limitation in H.225 (and H.245) on how
>nonStandardData is included in messages.  Basically only one
>non-standard element can be included in each PDU.  This is because of
>the syntax:
>        nonStandardData NonStandardParameter,
>What is really required for a truly extensible protocol is:
>        nonStandardData SEQUENCE OF NonStandardParameter,
>This is especially important if a gatekeeper wants to insert
>nonStandardData into a message that already has nonStandardData added in
>to it by an endpoint.
>This may be too late to fix for H.225, but we can fix this for the
>H.450.x protocols.
>Pete Cordell
>BT Labs
>E-Mail: pete.cordell at
>Tel: +44 1473 646436
>Fax: +44 1473 645499

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