scope:

Computer-Aided Software Engineering (CASE) tools are used to describe the behavior of software using a variety of different design notations. These may be graphical or textual in nature, or they may be a combination. This standard provides a reference model of fundamental software concepts that form the "building blocks" for a number of these commonly used notations. This standard also includes a textual language, the Semantic Transfer Language (STL), for representing software application behavior descriptions. A software behavior description consists of a collection of sentences that conform to the formal syntax of the STL and that are to be interpreted in terms of the software concepts defined in this standard. The STL syntax is designed to be computer-parsable, while remaining easy for users to read and write. This reference model and transfer syntax may be used for directly recording, storing, and analyzing a software behavior description, as well as for transferring elements of a software behavior description between CASE tools.

This standard excludes the structural descriptions of software product designs or implementations, and it does not provide a traceable decomposition of software into programs, modules, subroutines, or objects. However, it does provide the means to describe the functions and behavior of a program, module, subroutine, or object.

This standard focuses on the semantics of information concerning software behavior, not on graphical representations for that information. Graphical information is not important when communicating among tools that do not need to reproduce the same drawing. However, the STL defined in this standard does include references to images or drawings of graphical symbols that may be used to indicate correspondences between graphical and textual representations of the same software concepts.

Purpose

The purpose of this standard is to specify a common set of modeling concepts based on those found in commercial CASE tools for describing the operational behavior of a software product. This standard establishes a uniform, integrated model of software concepts related to software functionality. It also provides a textual syntax for expressing the common properties (attributes and relationships) of those concepts as they have been used to model software behavior. The 1175.3 exchange syntax is both machineprocessable and human-readable.

As an alternative to establishing direct tool-tool mappings as the basis for information sharing among CASE tools, this standard identifies a common set of "tool-neutral" modeling concepts. By mapping their internal data into the common STL syntax provided by this standard, and by exchanging data files constructed using the STL, it becomes possible for two different CASE tools to reliably exchange descriptions of a subject software application. As each tool can map its own meta-model constructs against the standard 1175.3 software behavior concepts, it is not necessary for any one tool to understand the internal structures of another tool. This also means that a number of tools can exchange descriptions on the basis of one set of concept mappings per tool, a substantial reduction of effort from the pairwise mapping approach.

In addition to tool-tool information exchange applications, the STL has also been found to be useful for design reviews, a form of tool-user interconnection. Because the STL is straightforward to write, and is much like everyday English sentences, it is also possible to employ the STL for user-user and user-tool information exchange applications.

This standard incorporates and extends the material in Part 3 of IEEE Std 1175^TM-1991 [B5].¹ For backward compatibility, this standard does not change any of the syntax or conformance aspects of the STL as defined in Part 3 of IEEE Std 1175-1991 [B5].² The primary emphasis for this revision has been to improve the clarity and usability of the material for its original intended purposes, rather than to revise the content or otherwise update it to incorporate and represent the software methodology developments of the 1990s.

¹The numbers in brackets correspond to those of the bibliography in Annex F.

²However, additional syntax has been added to provide a standardized form for conditional expressions. These were left as a userdefined item in IEEE Std 1175-1991 [B5].