Information technology -- Processing languages -- Document Style Semantics and Specification Language (DSSSL)

Traitement de l'information -- Processing Langage -- Sémantique de présentation de documents et langage de spécifications (DSSSL)

Forword

ISO (the International Organization for Standardization) and the IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work.

In the field of information technology, ISO and IEC have established a joint technical commitee, ISO/IEC JTC 1 . Draft International Standards adopted by the joint technical committee are circulated to national bod es for voting. Publication as an International Standard requires approval by at least 75% of the national bodies to vote.

Introduction

This International Standard defines the Document Style Semantics and Specification Language (DSSSL) used to specify the formatting and transformation of SGML documents. The initial focus of DSSSL is on formatting for both paper and electronic media and on the transformation of SGML documents marked up according to different DTDs. DSSSL may be used with any SGML documents without requiring modifications or constraining the document type definitions.

The main objective of this International Standard is to provide a language for expressing formatting and other document processing specifications in a formal and rigorous manner so that these specifications may be processed by a broad range of formatters, either natively or using a translation mechanism.

The DSSSL style language allows users to specify the types of formatting to be applied to various objects during composition, layout, and pagination. The DSSSL transformation language allows users to specify the transformation of documents from one application of SGML markup into another.

DSSSL is designed for specifications that apply to a class of documents. These specifications are applicable to all possible SGML documents for an SGML application as well as to a particular SGML document.

The DSSSL specification languages are declarative. They are not intended to be complete programming languages, although they contain constructs normally associated with such languages. DSSSL specifications can be unambiguously parsed and interpreted by heterogeneous systems. In addition, DSSSL specifications may be used by existing formatting systems through the use of “front-end” DSSSL processors and translators. DSSSL has no bias toward batch or interactive formatting systems and does not prescribe any pre-defined formatting algorithms.

The standardization of formatting semantics is provided in DSSSL through a set of basic structures known as flow objects and an associated set of formatting characteristics that are applied to those objects. DSSSL provides mechanisms for defining and extending the semantic constructs so that DSSSL application designers can construct DSSSL applications best suited to their application environments.

Background

The concepts behind DSSSL are associated with the development of generic coding and specifically with SGML, the Standard Generalized Markup Language (ISO 8879).

Historically, electronic manuscripts contained control codes or macro calls that caused the document to be formatted in a particular way (“specific coding”). In contrast, generic coding, which began in the late 1960s, uses descriptive tags (for example, “heading” rather than “Space 3 lines; 14 point Bodoni”). Central to the concept of generic coding is the separation of the information content of documents from the format or appearance of the content. The generic coding concept gained prominence in the early 1970s and came to fruition with the development of SGML.

While SGML provides the language for modeling classes of documents, it does not prescribe any particular model or pre-defined tag set. A set of rules (consisting primarily of a DTD and its supporting documentation) that applies SGML to a class of documents is known as an SGML application.

SGML standardizes the representation of the document structure, leaving it to users to develop their own techniques for interfacing with formatters and other processors, such as general purpose translators. DSSSL is designed to support this second class of applications by providing a standardized architecture for formatting and other processing specifications, allowing users to interchange such specifications within a standardized framework.

A DSSSL specification is normally external to the SGML document to which it applies, and thus multiple specifications may be applied to a given SGML document to yield various presentations of the same data.

SGML provides the ability to distinguish between the intrinsic content and structure of a document, on the one hand, and the specifications for processing it on the other. With DSSSL, formatting and other processing specifications may be interchanged in conjunction with SGML documents to provide the standardized specification of document display while preserving the essential distinction between content and format.