Subject: Misleading ABNF Comment (servChgReplyParm)

From: David Dykhuizen <[email-masked]>
Date: Fri, 3 Nov 2000 07:41:51 -0600

Morning:

We've looked in the Implementors' Guide for H.248 (Draft_V3) and
the mail archive but have not found the following "issue" addressed.

According to the ASN.1 definition, reading the comment above the
ServiceChangeResult parameter definition, we have:

"-- For ServiceChangeResult, no parameters are mandatory. Hence the
 -- distinction between ServiceChangeParm and ServiceChangeResParm."

If we look at the ASN.1 definition for ServiceChangeResParm, all elements
are optional.

Now when we look at the ABNF definition, and reading the comment
above the servChgReplyParm parameter:

" ; at-most-once. Version is REQUIRED on first ServiceChange response"

Going back to chapter 7.2.8 in the main specification, towards the
end of the chapter we have the following statement:

The return from ServiceChange is empty except when the Root termination
is used. In that case it includes the following parameters as required:

...  some text deleted for brevity ...

* ServiceChangeVersion, if the responder wishes to negotiate the version
  of the protocol to be used for the association.

Therefore, I suggest that the comment "Version is REQUIRED on first
ServiceChange response" be removed.

Thanks,
/David