John,
You stated:
I agree with Peter, CMS should allow the extension of the Choice syntax
i.e. in text using the old ASN.1 rules), which gives a good pointer to the
implementors that they should not object if the they receive an extended
choice.
I agree that the CMS RecipientInfo CHOICE syntax could be modified in future
versions of CMS through the addition of well-defined ASN.1 syntaxes, but I
disagree that adding "..." in the current CMS RecipientInfo syntax adds any
value. If your use of "extended choice" refers to a RecipientInfo including
a CHOICE alternative not specified in the CMS document, then I object to
your statement that implementors "should not object if the they receive an
extended choice." Please see my previous message for the explanation of why
I object to the premise that it is straightforward for recipient software to
ignore undefined CHOICE alternatives.
- John Pawling