The Standard Generalized Markup Language (ISO 8879:1986 SGML) is an ISO-standard technology for defining generalized markup languages for documents. ISO 8879 Annex A.1 defines generalized markup:
Markup should be declarative: it should describe a document's structure and other attributes, rather than specify the processing to be performed on it. Declarative markup is less likely to conflict with unforeseen future processing needs and techniques.
Markup should be rigorous so that the techniques available for processing rigorously-defined objects like programs and databases can be used for processing documents as well.
GML (Generalized Markup Language) is an IBM document-formatting language that describes a document in terms of its organization structure and content parts and their relationship. GML markup or tag s describe such parts as chapters, important sections and less important sections (by specifying heading levels), paragraphs, lists, tables, and so forth. GML frees document creators from specific document formatting concerns such as font specification, line spacing, and page layout required by IBM's printer formatting language, SCRIPT.
GML Starter Set is the name of IBM's set of GML tags. GML Starter Set input is processed by the Document Composition Facility (DCF) which formats printer-ready output. A later and more capable set of GML tags is provided by IBM's BookMaster product.
GML preceded and was an inspiration for the industry-developed Standard Generalized Markup Language ( SGML ), today's strategic set of rules for creating any structured document description language. This Web page is marked up with Hypertext Markup Language ( HTML ) tags and is an example of a document that makes use of GML concepts. The Extensible Markup Language ( XML ) also has roots in GML.