machine in the range. . System Programming Languages: S3 and SFL The primary language used for developing both the VME operating system itself and other system software such as compilers and transaction processing monitors is S3. This is a high level language based in many ways on Algol 68, but with data types and low-level functions and operators aligned closely with the architecture of the 2900 series. An assembly language SFL (System Function Language) is also available. This was used for the development of VME/K, whose designers were not confident that a high-level language could give adequate performance, and also for the IDMS database system on account of its origins as a third-party product. SFL was originally called Macro Assembler Programming LanguagE (MAPLE), but as the 2900 architecture was being positioned as consisting of high level language machines the name was changed at the request of ICL Marketing. It had been developed as a part of the toolkit for System D, which was subsequently cancelled. Related families of assemblers for other architectures (CALM-xx running under VME, PALM-xx developed in Pascal and running on various hosts) were developed for internal use. Neither S3 nor SFL was ever promoted as a commercial development tool for end-user applications, as neither were normally delivered as a standard part of the operating system, nor were they explicitly marketed as products in their own right. Both SFL and S3 were however available as options to user organisations and third parties who had a specific need for them. QuickBuild The QuickBuild application development environment on VME has been highly successful despite the fact that applications are largely locked into the VME environment. This environment is centred on the Data Dictionary System (DDS, also called OpenDDS), an early and very successful attempt to build a comprehensive repository supporting all the other tools, with full support for the development lifecycle. As well as database schemas and file and record descriptions, the dictionary keeps track of objects such as reports and queries, screen designs, and 4GL code; it also supports a variety of models at the requirements capture level, such as entity-relationship models and process models. The QuickBuild 4GL is packaged in two forms: ApplicationMaster for the creation of online TP applications ReportMaster for batch reporting. Both are high-level declarative languages, using Jackson Structured Programming as their design paradigm. ApplicationMaster is unusual in its approach to application design in that