This Supplement is published as a Supplement to Recommendation Z.100 (SDL), but is also relevant to Recommenda­tions Z.105 (SDL with ASN.1) and Z.120 (MSC). It outlines a methodology for the use of these languages in combination.

This Supplement covers the following topics:

1)          Terminology definitions and background material on the use and application of SDL;

2)          An overview of the methodology (clause 4);

3)          More detailed descriptions of:

a)          Analysis of the requirements (clause 5);

b)          Draft Design and investigation of the application (clause 6);

c)           Formalization of the application into SDL+ (clause 7);

d)          Implementation issues (clause 8);

e)          Validation (clause 9);

4)          Relationship with other languages and techniques;

5)          An elaboration of the methodology for service specification.

This Supplement is not exhaustive. It is intended to be incorporated by the SDL+ users in their overall methodologies, and tailored for their application systems and specific needs. In particular, this Supplement does not cover the issues of derivation of an implementation from the specification or the testing of systems in detail. In the case of testing, it is expected that this should be partially covered by a separate document dealing with the generation of tests for standards or products based on SDL+.

The methodology is a framework to be elaborated for the context of actual use. This Supplement has two parts. In Part I the framework is explained as an overview in clause 4, with a more detailed description of the main parts in clauses 5, 6 and 7. The general framework is then specialized for the case of services specification in Part II starting at clause 12. The parts from clauses 5, 6 and 7 are elaborated in clauses 13, 14 and 15. In this specialization some choices of approach have been made. Many of the details given in clauses 13, 14 and 15 can be used when the general framework is elaborated for other contexts and other choices.