An introduction to the Specification and Description Language (SDL), the most widely used language in the telecommunications industry, up to its revisions of 1996. Designed to train readers how to program SDL specifications, topics include basic concepts, how to structure large specifications, the object-oriented features of SDL incorporated in 1992, general lexical and syntax rules, data types including ASN.1, the interpretation model of the language, and the layered specification of protocols and services. Annotation c. by Book News, Inc., Portland, Or.