Hi Ramaswamy,

I have not seen anyone else respond to your question about the constructed
BitString encoding so I though I might help.

Please see the following subclauses from X.690:

8.6.1   The encoding of a bitstring value shall be either primitive or
constructed at the option of the sender.
NOTE - Where it is necessary to transfer part of a bit string before the
entire bitstring is available, the constructed encoding is used.

8.6.3   The contents octets for the constructed encoding shall consist of
zero, one, or more nested encodings.
NOTE - Each such encoding includes identifier, length, and contents
octets, and may include end-of-contents octets if it is constructed.

There is no limit to how deeply nested these constructed encodings can be,
however, some ASN.1 tools impose artificial limits for security reasons.

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On Mon, 29 Nov 2004, Ramaswamy R wrote:

> Hi,
>
> In ITUT-X.690 clause 8.6.1 (Note) it is mentioned that - "Where it is
> necessary to transfer part of a bit string before the entire bitstring
> is available, the constructed encoding is used".
>
> If my understanding is correct, the constructed encoding is never
> applicable for a BitString member contained in an aggregate
> (constructed) type. Since the constructed type cannot be transmitted
> in parts, the encoding of a BitString anywhere within a constructed
> type would always be subjected to primitive encoding.
>
> Is it correct to assume that the constructed encoding of a BitStream
> is applicable only when the BitStream itself is the PDU and not
> otherwise?
>
> If this is not the case, kindly explain the other possible scenario
> where the constructed encoding is applicable.
>
> Regards
> Ramaswamy
> ============================
> "Do or Do Not, there is No Try" - Yoda
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