GSM 09.02 - Version 5.3.0 - Digital cellular telecommunications - ETSI

Page 198
GSM 09.02 version 5.3.0: August 1996
14.1.4 Compatibility considerations
The following ASN.1 modules are conforming with CCITT Recommendation X.208 (1988), but in addition
Ellipsis Notation ("..." - notation) is used as described in ISO 8824-1/PDAM 3.2 wherever future protocol
extensions are foreseen.
The "..." construct only applies to a SEQUENCE. An entity supporting a version greater 1 shall not reject
unsupported extension following "..." of that SEQUENCE. The Encoding Rules from subclause 14.1.1 apply
to every element of the whole Transfer Syntax especially to the ASN.1 type EXTERNAL.
Note that the Ellipses Notation is not supported in a version 1 context. Therefore a SEQUENCE sent in a
version 1 context shall not include any element following "...".
NOTE: Every extension has to follow the superset mechanism defined in ETR 060.
Any change other than in the extension area leads to a new Application Context
version.
PLMN specific extensions shall follow the extension marker and shall be tagged using PRIVATE tags up to
and including 29.
The Abstract Syntaxes of MAP version 2 are in general an extension of the Abstract Syntaxes of MAP
version 1. They are therefore (in general) backward compatible with MAP v1 from the Abstract Syntax
point of View. Exceptions from this backward compatible changes of the Abstract Syntax were made only
for the following reasons:
i) information element was not used by a GSM phase 1 service due to missing or unstable phase 1
service description (e.g. Closed User Group);
ii) information element used only on the MSC-VLR Interface
(e.g. SendInformationForIncomingCallSetUp);
iii) changes with impact only in the error situation (e.g. different Cause Values);
iv) changes on the MAP-AbortInfo.
Changes without impact on the Transfer Syntax are not indicated (e.g. name changes, introduction of
extension marker).
Information Elements added in existing Constructs for version 2 or information elements kept only for
compatibility with version 1 are indicated by ASN.1 comments These comments state which subset of the
abstract syntax must be used in the negotiated application context.