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
============================================
dr. Gy�rgy R�THY
Ericsson Communications Systems Hungary Lim.
Conformance Center
tel.: +36 1 437-7006; fax: +36 1 437-7767
mobile: +36 30 297-7862
e-mail: [EMAIL PROTECTED]
web: http://www.r.eth.ericsson.se/~ethgry
============================================
>-----Original Message-----
>From: Egon Andersen, Talura [mailto:[EMAIL PROTECTED]]
>Sent: Friday, January 18, 2002 8:39 AM
>To: [EMAIL PROTECTED]
>Subject: Re: [ASN.1] Is this a legal SEQUENCE ?
>
>
>> Ed Day wrote:
>>
>> Hi,
>>
>> I have come across the following definition in a spec which
>I believe to be legal:
>>
>> MAP-AcceptInfo ::= SEQUENCE {
>> ...,
>> extensionContainer ExtensionContainer OPTIONAL
>> -- extensionContainer must not be used in version 2
>> }
>> Yet, this does not seem parsable by the rules as currently
>stated in X.680.
>>
>> When decomposed, the rule for SequenceType would appear to
>have only two possibilities for a type starting with an
>extension marker:
>>
>> SEQUENCE { ExtensionAndException OptionalExtensionMarker }
>>
>> or (via ComponentTypeLists):
>>
>> SEQUENCE { ExtensionAndException ExtensionAdditions
>ExtensionEndMarker , RootComponentTypeList }
>>
>> It does not appear that either of these allows the above
>construct to be handled. Is the type definition wrong or are
>the rules wrong or am I missing something? (and yes, I went
>back to read the Corrigenda to see if this was corrected anywhere).
>>
>> Regards,
>>
>> Ed Day
>> Principal Engineer
>> Objective Systems, Inc.
>> [EMAIL PROTECTED]
>> (484) 875-3020 (main)
>> (610) 608-4930 (mobile)
>> (610) 321-0361 (fax)
>> (877) 307-6855 (toll-free)
>>
>>
>>
>I've reported this as an error in the 1997 version of ASN.1.
>I believe it will be corrected and included in the 2002 version of
>ASN.1.
>(Atleast that was promissed to me by Olivier Dubuisson approx. half a
>year ago.)
>
>Best regards
>Egon Andersen
>--
>* Talura ApS * Phone: +45 43 52 50 00 *
>* Baldersh�j 24 B * mailto:[EMAIL PROTECTED] *
>* DK-2635 Ish�j * http://www.talura.dk *
>
