> Rajul,
>
> Okay, thanks. So I think you're answer to my first question is, yes. :-)
>
> Also, given X:
>
> X ::= SEQUENCE {
> a INTEGER, -- stuff...
> b BOOLEAN
> }
>
> I believe that Z1:
>
> Z1 ::= SEQUENCE {
> y TYPE-IDENTIFIER.&Type (X)
> }
>
> encodes in PER exactly like Z2:
>
> Z2 ::= SEQUENCE {
> y OCTET STRING -- contains X
> }
>
> True?Hi Paul, Yes, it's true. it will be encoded like OCTET STRING. Rajul Gupta OSS Nokalva (www.oss.com) [EMAIL PROTECTED] (732) 302-9669 (x137) > Paul Long > ipDialog, Inc. > > > -----Original Message----- > > From: Rajul Gupta [mailto:[EMAIL PROTECTED]] > > Sent: Monday, June 24, 2002 4:13 PM > > To: [EMAIL PROTECTED] > > Cc: [EMAIL PROTECTED] > > Subject: Re: [ASN.1] TYPE-IDENTIFIER.&Type > > > > > > Hi Paul, > > > > (X) is a type constraints here, and it says that "y" MUST be of type "X" > > only. Syntactically, this is equivalent to > > > > Z ::= SEQUENCE { > > y X > > } > > > > However, this kind of syntax (your syntax) is useful in case of PER. PER > > always doesn't have length encoded, but while encoding open > > types, PER puts > > a length wrapper also. So if you are using PER, then at the decoding side > > you can easily find out the length of encoded open type value, without > > knowing it's type. > > > > Usually this type of construct is useful for security fields. Using length > > wrapper you can easily find out the length of security data and leave this > > data unwrapped and unprocessed in your application, and pass it to other > > application or function, where this security data is used. > > > > I hope this answer could be helpful for you. > > > > Rajul > > > > > I've put it off too long. Now it's time for me learn this ".&" stuff. Is > > y, > > > below, encoded in PER as an open type that contains an encoding of X? Is > > > that all there is to it? > > > Also, what syntactical role does the "(X)" play? Is > > > this a constraint and otherwise y could be encoded as an open > > type of any > > > type? > > > X ::= SEQUENCE { > > > a INTEGER, -- stuff... > > > b BOOLEAN > > > } > > > > > > Z ::= SEQUENCE { > > > y TYPE-IDENTIFIER.&Type (X) > > > } > > > > > > Paul Long > > > ipDialog, Inc. > > > > > > > > > > > > > > > >
