John et al,
See below.
-----Original Message-----
From: John Pawling <jsp(_at_)jgvandyke(_dot_)com>
To: ietf-smime(_at_)imc(_dot_)org <ietf-smime(_at_)imc(_dot_)org>
Date: Tuesday, January 20, 1998 07:53
Subject: Re: Content Type Attribute Question
This results in the following:
ContentTypeExtended ::= CHOICE {
built-in BuiltInContentType,
external ExternalContentType,
externalWithSubtype ExternalContentWithSubtype,
other [0] OtherContentType }
I would like to raise a general concern with definition of structures based
on ASN.1 CHOICE. I personally prefer it if definitions like this had
context-specific tags of every field.
e.g. This definition would be as follows:
ContentTypeExtended ::= CHOICE {
built-in [0] BuiltInContentType,
external [1] ExternalContentType,
externalWithSubtype [2] ExternalContentWithSubtype,
other [3] OtherContentType }
That way we would not have to rely of the definition of BuiltInContentType,
ExternalContentType and ExternalContentWithSubtype being unique from a tag
perspective, and if they ever changed we would not have to worry about
amending this definition retrospectively.
This is a general case "rule" that I believe we should follow for future
definitions that use CHOICE. I am NOT proposing that we change this
particular structure now as it would not be backwards compatible, and
backwards compatability is an issue (on this list at least).
All things considered, I agree with John's changes.
Darren
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