 The description of the next release should include the list of faults fixed. There are a range of methods using graphics based techniques which may be grouped together under this heading. The most commonly known ones in the telecommunications industry are JSD, SDL, 25.2.9.2 Enhancements SADT, Yourdon and the Yourdon based RT-SASD. These will be triggered either by a set of approved Change Requests, In general they address the portion of the lifecycle from the start or by the internal development plans for the system. of the Specification stage through to the end of the detailed design The lifecycle for the enhancements will be largely the same as for stage. (JSD addresses design stage only). Supporting tools often the main development. Care must be taken to ensure that all do- provide facilities for Requirements Capture, limited automatic code cumentation (requirements, specifications, design, comments in the generation and occasionally some automatic generation of tests. code, test specifications, user manuals) is kept fully up to date. These methods provide support for describing data (in abstract and implementation terms) via Entity Relationship Diagrams and Entity life histories, data transformations (via Data Flow Diagrams) 25.3 Software design techniques and behaviour (via State Transition Diagrams and event lists). Control is shown via Control Flow Diagrams, and the structure of There are many different software development techniques avail- the software is shown in a variety of ways (for example structure able; each addresses a particular section of the overall lifecycle and charts). is applicable to a specific range of software applications. This The method itself defines how to utilise these techniques to section provides an overview of the main techniques used in the provide a complete specification, and then to derive the architectu- development of software in the telecommunication industry. ral and detailed designs in a way to produce a modular system with The main methodologies may be grouped under