Re: Cross-purpose SEQUENCE/CHOICE protocol extension fields

[Rici Lake <rici@ricilake.net>]

On 8-Nov-04, at 7:48 PM, Steven Legg wrote:

> If one follows the ASN.1 rules for extensibility then a known
> element will never follow an unknown element.

Surely that is not true. If there is an extension marker in
the base specification, that's where extensions go; there is
no requirement that it be at the end. Furthermore, there might
be an extensible CHOICE in the middle of a SEQUENCE.

X.680 (07/2002), 48.1 (just after a note that extension markers
have no effect on BER); "The extension marker ... makes no statement
as to how such additions should be handled other than that they
should not be treated as an error during the decoding process."