Re: Grammars, Ambiguous, ASN.1

Hi,


sge@acm.org (Steve Elkins) asked about ASN.1 grammar. [I lost his
original post, sorry.]


I forgot to mention in my previous reply that three technical corrigenda
must be applied to X.208, in order to remove another ambiguity (these
corrigenda are given in X.680:1994), and to be compliant of course:


AnyValue ::= Type ":" Value instead
of AnyValue ::= Type Value
ChoiceValue ::= identifier ":" Value | Value instead
of ChoiceValue ::= NamedValue
SelectionValue ::= Value
instead of SelectionValue ::= NamedValue


This avoid nasty things like:


x T ::= a b c U ::= NULL


that may have been interpreted either like


x T ::= a b c
U ::= NULL


or


x T ::= a b
c U ::= NULL


Best regards,


--


Christian


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