On Thu, 27 Dec 2001, ASN Dev wrote:
>
> Hi:
>
> I am a ASN.1 newbie and trying to understand the
> following ASN.1 declaration
>
> EMBEDDED PDV (WITH COMPONENTS { ...,
> identification (WITH COMPONENTS { ...,
> presentation-context-id ABSENT,
> context-negotiation ABSENT }) })
>
> How do I interpret 'WITH COMPONENTS' in the above
> declaration ? What exactly does 'WITH COMPONENTS' imply ?
>
> Thanks for your time in advance.
Given: The EMBEDDED PDV type contains three components - "identification",
"data-value-descriptor" and "data-value".
In "WITH COMPONENTS" the presence of the sequence of the characters "{
..., " immediately after "WITH COMPONENTS" (space not being significant)
effectively states that what follows is an assertion on whatever
component(s) are explicitly listed in the constraints, and that no
assertion is being made on any component not explicitly listed. For
example, in the above constraint on EMBEDDED PDV, the outer "WITH
COMPONENTS" is an assertion on the value of "identification", and is
silent on the value of "data-value-descriptor" and "data-value".
The assertion being made on "identification" is itself a "WITH COMPONENTS"
constraint. You can read it as saying - "As far as this constraint goes
there is no restriction on 'identification', with the exception that the
components 'presentation-context-id' and 'context-negotiation' MUST be
absent in all values of 'identification'."
> What exactly does 'WITH COMPONENTS' imply ?
It imposes a constraint on the components of a previously defined SET,
SEQUENCE or CHOICE type, or on a type derived from these, such as EMBEDDED
PDV.
-------------------------------------------------------------------------
Bancroft Scott Toll Free :1-888-OSS-ASN1
OSS Nokalva International:1-732-302-0750
[EMAIL PROTECTED] Tech Support :1-732-302-9669 x-1
1-732-302-9669 x-200 Fax :1-732-302-0023
http://www.oss.com
