8 Further Work

guage. Hence, an SGML browser can be used to browse LISP, Ada or COBOL. For languages such as FORTRAN that may be \diicult" to parse, we could replace the DTD-driven parser with a programming-language-dependent parser. In fact, if the SGML representation of a programming language could be standardized, then every compiler could include an option that would generate the SGML equivalent of the input program. After all, during compilation, all the information about the semantics of the program is collected and it would not be a diicult task to produce an SGML tagged program. For example, as part of the eeort to standardize the formal speciication language Z 14], the ISO committee decided to include a DTD description of the language with the standards proposal 15]. Raymond stated \source code can beneet from document formatting and typesetting technology" 6] but it can also beneet from text database technology. SGML is a rich metalanguage able to describe source code. Because many organizations including departments of the U.S. Government are promoting the use of SGML as a standard method for document interchange , there are many diierent vendors supplying tools to manipulate SGML text. A software system is deened by a collection of documents which are processed at various stages into human and machine readable formats. Such documentation includes system documentation, user guides, diagrams, program source code, and various graphics. All this documentation could be maintained in an SGML format and supported by various DTDs and style sheets. Hypertext links could be supported by the tag set so that the reader could browse through connected chunks of information. An important step would be to have the documentation including program code for the entire software system stored in a text database with the proper tools to support browsing, and editing in a WYSIWYG environment. The style sheets could support communication with compilers and similar tools. Thus, the database would support views of the software project and would allow updates through those views. Such a text database might be used to support a software engineering environment, although other issues such as version control have to be considered. We are currently investigating the use of text databases to support software engineering environments with a view to taking advantage of concepts and tools related to tagging and SGML. 9 Conclusions In this paper we describe the use of SGML to tag program source code for the …