Designed to specify the processing of valid SGML documents. DSSSL defines the semantics, syntax, and processing model of two languages for the specification of document processing: a) The transformation language for transforming SGML documents marked up in accordance with one or more DTD's. b) The style language, where the result is achieved by applying a set of formatting characteristics to portions of the data, and the specification is, therefore, as precise as the application requires, leaving some formatting decisions, such as line-end and column-end decisions, to the composition and layout process.