Olivier Dubuisson wrote:
>
> "Egon Andersen, Talura" wrote:
> >
> > Hi,
> >
> > I came across the following notation:
> >
> > MyType1 ::= SEQUENCE {
> > ...,
> > ...}
> >
> > This seems to be perfectly legal according to X.680 (1997 E) clause 24.1
> >
> > According to 3.8.29 the 'extension insertion point' is in between the
> > two ellipsis.
> >
> > MyType2 ::= SEQUENCE {
> > ...,
> > alpha INTEGER,
> > ...}
> >
> > should then be the propper way to extend with a NamedType.
> >
> > But this does not comply to any of the alternatives in
> > ComponentTypeLists.
> > All alternatives in ComponentTypeLists requires a RootComponentTypeList,
> > which is non-empty.
>
> Good catch! I'll make sure that this will be mended in the 2002 edition of
> the ASN.1 standard.
>
> > How do I extend MyType1 according to X.680 (1997 E)?
> >
> > In the X.680 (1994 E)/Amd.1(1995 E) the notations would have been:
> > MyType3 ::= SEQUENCE {...}
> > and extended to:
> > MyType4 ::= SEQUENCE {..., alpha INTEGER}
>
> Correct. You can use it, for it's not worth having a second extension marker
> when the extension root is not splitted in two parts. Anyway 24.1 needs to
> be mended.
Yes, the above is valid X.680 (1994 E)/Amd.1(1995 E) syntax, but any
fully X.680 (1997 E) compatible compiler will make a syntax-error on
this construction!
So we actually also lost backward-compatibility!
(I've sent a defect report on this.)
Best regards
Egon Andersen
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