"Gyorgy Rethy (ETH)" wrote:
>
> Hi,
>
> looking at the ASN.1 2002 draft there is an addition (the last alternative of
>ComponentTypeLists) related to this issue; the current bnf looks like this (if there
>is no newer version):
> SequenceType ::=
> SEQUENCE "{" "}" |
> SEQUENCE "{" ExtensionAndException
>OptionalExtensionMarker "}" |
> SEQUENCE "{" ComponentTypeLists "}"
> ExtensionAndException ::= "..." | "..." ExceptionSpec
> OptionalExtensionMarker ::= "," "..." | empty
> ComponentTypeLists ::= RootComponentTypeList |
> RootComponentTypeList "," ExtensionAndException
>ExtensionAdditions OptionalExtensionMarker |
> RootComponentTypeList "," ExtensionAndException
>ExtensionAdditions ExtensionEndMarker ","
> RootComponentTypeList |
> ExtensionAndException ExtensionAdditions
>ExtensionEndMarker "," RootComponentTypeList |
> ExtensionAndException ExtensionAdditions ExtensionEndMarker
>
> RootComponentTypeList ::= ComponentTypeList
> ExtensionEndMarker ::= "," "..."
> ExtensionAdditions ::= "," ExtensionAdditionList | empty
> etc.
>
> According to this bnf the type definition below is illegal, because the
>ExtensionEndMarker does not have an "empty" path. But I think, a second extension
>marker is not really necessary in this case and the last alternative of
>ComponentTypeLists could be changed to (it would make this alternative to "rhyme"
>with the second altenative of SequenceType):
>
> ExtensionAndException ExtensionAdditions
>OptionalExtensionMarker
>
> With this change in the bnf the quoted type would become legal.
>
> Best Regards, Gy�rgy
>
It would be better to use:
ExtensionAndException "," ExtensionAdditionList OptionalExtensionMarker
because the other solutions will give multiple ways through the BNF.
Best regards
Egon Andersen
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