Standard Generalized Markup Language (SGML) is an international standard defining the structure of documents.
SGML…
- Offers freedom from proprietary software and hardware systems--document managers can choose "best of breed" tools to create, manage, or retrieve data.
- Documents marked up in SGML allow control over revision and reversion--when stored in an SGML database; original data is archived alongside any changes.
- Is a vendor independent language--the format of your data does not need to be changed based on its publication media.
- Information needs only to be created once and re-used--no need to duplicate effort when there are changes to product specifications.
- SGML automated processes make it possible to target specific information--offering shorter production cycles, better electronic production, and minimal updates.
SGML: A Time Line…
- 1967 – the concept of a generic mark-up language was first discussed at a meeting between the Graphics Communication Association and the Government Printing Office
- 1970’s – first publication of a standard for the first generic mark-up language (GML).
- 1978 – First version of SGML published as a Graphics Communication Association Standard.
- 1986 – Revised version of SGML published as an international standard (ISO 8879). This is the definitive version of SGML in use today.
SGML Documents Consist Of…
- Document Declaration – specifies basic facts about the "dialect" of the SGML being used.
- Document Type Definition (DTD) – specifies the actual tag names, the relationship between the tags, the order in which they appear in the document, and any qualifying attributes which apply to individual tags. Also, defines the format for linkages to other documents.
- Document Instance – actual text of the document with the SGML tags embedded, identifying the various parts of the text (Document Instance can share a DTD w/several other documents, but can only conform to one DTD itself and cannot draw on tagset, defaults, or definitions from several DTD’s).
- Output Specification – varies information about the formatting of specific text elements (ex, typeface, indention, and font size).
SGML Applications…
- The World Wide Web currently uses HTML, a reduced tagset version of SGML, to encode its documents.
- The Department of Defense and its defense contractors often use SGML encoded documents to exchange data, bids, and technical specifications.
- The Text Encoding Initiative, a consortium of academic institutions, is using SGML to make available electronic versions of texts in the humanities for scholarly study.
- SGML is used to create Braille and large print books for the visually impaired and physically challenged.