Error in H.323v3 ASN.1

Logan Modahala lmodahal at CISCO.COM
Fri Oct 6 12:43:53 EDT 2000


Please see my email posted today on this issue describing the

- Logan

Paul Long wrote:
> Bancroft,
> These components are in a CHOICE type, so the clause that you specify has
> nothing to do with our discussion. I think your response assumes they are in
> a SEQUENCE type.
> Also, by "do not use," I meant that, upon receipt, these choices are to be
> semantically treated as another, generic choice, undefinedReason and that
> they are to no longer be transmitted. Again, these are CHOICE, not SEQUENCE
> components.
> Paul Long
> Smith Micro Software, Inc.
> -----Original Message-----
> From: Bancroft Scott [mailto:baos at OSS.COM]
> Sent: Friday, October 06, 2000 4:17 AM
> Subject: Re: Error in H.323v3 ASN.1
> On Thu, 5 Oct 2000, Paul Long wrote:
> <snip>
> Unless I am misunderstanding what you are saying, the "-- do not use"
> will
> not work if the receiver is using an earlier version in which the "-- do
> not use" type is defined, for it violates X.680 clause 24.14:
>    24.14 A value for a given extension addition type shall not be
>    specified unless there are values specified for all extension
> addition
>    types not marked OPTIONAL or DEFAULT that lie logically between the
>    extension addition type and the extension root.
>    NOTE 1 -Where the type has grown from the extension root (version 1)
>    through version 2 to version 3 by the addition of extension
> additions,
>    the presence in an encoding of any addition from version 3 requires
> the
>    presence of an encoding of all additions in version 2 that are not
>    marked OPTIONAL or DEFAULT.
> Omitting OPTIONAL and DEFAULT from an extension addition definition
> means
> that an extension addition value is mandatory in messages that are
> originated by an implementation in which such extension additions are
> defined, which implies that an encoding cannot have a missing mandatory
> extension addition value followed by any other component.
> The only way that interoperability can be achieved here is by the older
> version H.225 spec being changed to add OPTIONAL to those items marked
> with "-- do not use".  It will have no effect on the bits on the wire,
> other than to make such encodings valid.
> ------------------------------------------------------------------------
> -
> Bancroft Scott                               Toll Free
> :1-888-OSS-ASN1
> OSS Nokalva
> International:1-732-302-0750
> baos at                                 Tech Support
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