Hi Egon,
Thanks for your reply. I now go on to another aspect that i need to
understand.In my earlier mail i left out the below portion of the ASN.1
syntax, where an example of the the Information object class 'Extensions' is
presented namely the 'firstExtension'.
-- Example of addition of an extension named 'Some Network Specific
Indicator' of type
-- BOOLEAN, with criticality 'abort' and to be identified as extension
number 1
-- Example of definition using the above information object class:
--
-- SomeNetworkSpecificIndicator EXTENSION ::= {
-- EXTENSION-SYNTAX BOOLEAN
-- CRITICALITY abort
-- IDENTIFIED BY local: 1
-- }
-- Example of transfer syntax, using the ExtensionField datatype as
specified in subclause 5.
-- Assuming the value of the extension is set to TRUE, the extensions
parameter
-- becomes a Sequence of type INTEGER ::= 1, criticality ENUMERATED ::= 1
and value [1]
-- EXPLICIT BOOLEAN ::= TRUE.
--
-- Use of Q.1400 [28] defined Extension is for further study.
-- In addition the extension mechanism marker is used to identify the future
minor additions
-- to CAP.
firstExtension EXTENSION ::= {
EXTENSION-SYNTAX NULL
CRITICALITY ignore
IDENTIFIED BY local: 1
}
-- firstExtension is just an example
As mentioned earlier the spec. defins the supported extensions as
SupportedExtensions {PARAMETERS-BOUND : bound} EXTENSION ::=
> {firstExtension, ...
> -- full set of network operator extensions --
Does this throw any more light on how to interpret the constraint or is it
still erroneous? What significance do the words 'full set of network
operator extensions ' have? What significance does the example
firstExtension have?
Thanks,
Deepa.
.
-----Original Message-----
From: Egon Andersen, Talura [mailto:[EMAIL PROTECTED]]
Sent: Monday, December 11, 2000 1:54 AM
To: Bhan, Deepa
Subject: Re: A few questions regarding the infomation object classes in
3G29-0 78 v3.5.0-CAP implementaion.
Hi Deepa Bhan,
Specifications are not easier to understand, when there are syntactical
errors in them! (See below.) Please anyone, argue with or against me on
this, as I've seen this error in other specs too!
Your question is answered below
Bhan, Deepa wrote:
>
> Hi:
> I am studying the Cap spec. and there are a couple of things that i do not
> understand well
>
> 1. Extension field
>
> ExtensionField {PARAMETERS-BOUND : bound} ::= SEQUENCE {
> type EXTENSION.&id ({SupportedExtensions {bound}}),
>
> -- shall identify the value of an EXTENSION type
> criticality CriticalityType DEFAULT ignore,
> value [1] EXTENSION.&ExtensionType
>************> ({SupportedExtensions {bound}}{@type}),
>************> ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>************> This should be: DefinedObjectSet, but it isn't!
> ...
> }
> where
> SupportedExtensions {PARAMETERS-BOUND : bound} EXTENSION ::=
> {firstExtension, ...
> -- full set of network operator extensions --
>
> where
>
> EXTENSION ::= CLASS {
> &ExtensionType,
> &criticality CriticalityType DEFAULT ignore,
> &id Code
> }
>
> WITH SYNTAX {
> EXTENSION-SYNTAX &ExtensionType
> CRITICALITY &criticality
> IDENTIFIED BY &id
> }
>
> where bound is a instance of the Information object class
PARAMETERS-BOUND.
>
> How do i interpret all this? I believe SupportedExtensions is a table
> constraint in the ExtensionField sequence? What effect does Supported
> Extension have on the Extension Field.
Yes, it is meant to be a table-constraint
It is actually making a linking between 'type' and 'value', so that when
you receive a specific 'type', then you can determine the type of
'value'.
(X.682, chapter 10, do actually have a nice example explaining this.)
If we forget 'criticality' for the moment, you have a table of two
columns, and let's say 'type' is of type integer.
Given the following example:
&id ('type') | &ExtensionType ('value')
---------------------------------------
1 | INTEGER
7 | BOOLEAN
3 | OCTET STRING
---------------------------------------
Then when 'type' has the value: 7, then the type of 'value' is BOOLEAN
I hope this cleared a few things for you.
Best regards
Egon Andersen
--
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