language, text (SGML) A generic
markup language for
representing documents. SGML is an International Standard
that describes the relationship between a document's content
and its structure. SGML allows document-based information to
be shared and re-used across applications and computer
platforms in an open, vendor-neutral format. SGML is
sometimes compared to
SQL, in that it enables companies to
structure information in documents in an open fashion, so that
it can be accessed or re-used by any SGML-aware application
across multiple platforms.
SGML is defined in "ISO 8879:1986 Information processing --
Text and office systems -- Standard Generalized Markup
Language (SGML)", an
ISO standard produced by
JTC 1/SC 18
and amended by "Amendment 1:1988".
Unlike other common document file formats that represent both
content and presentation, SGML represents a document's content
data and structure (interrelationships among the data).
Removing the presentation from content establishes a neutral
format. SGML documents and the information in them can easily
SGML identifies document elements such as titles, paragraphs,
tables, and chapters as distinct objects, allowing users to
define the relationships between the objects for structuring
data in documents. The relationships between document
This is roughly analogous to a collection of
fielddefinitions in a
database. Once a document is converted
into SGML and the information has been 'tagged', it becomes a
database-like document. It can be searched, printed or even
programmatically manipulated by SGML-aware applications.
Companies are moving their documents into SGML for several
reasons:
Reuse - separation of content from presentation facilitates
Portability - SGML is an international, platform-independent,
standard based on
ASCII text, so companies can safely store
their documents in SGML without being tied to any one vendor.
Interchange - SGML is a core data standard that enables
SGML-aware applications to inter-operate and share data
seamlessly.
A central SGML document store can feed multiple processes in a
company, so managing and updating information is greatly
simplified. For example, when an aeroplane is delivered to a
customer, it comes with thousands of pages of documentation.
Distributing these on paper is expensive, so companies are
investigating publishing on CD-ROM. If a maintenance person
needs a guide for adjusting a plane's flight surfaces, a
viewing tool automatically assembles the relevant information
from the document
repository as a complete document. SGML
can be used to define attributes to information stored in
documents such as security levels.
There are few clear leaders in the SGML industry which, in
1993, was estimated to be worth US $520 million and is
projected to grow to over US $1.46 billion by 1998.
A wide variety tools can be used to create SGML systems. The
SGML industry can be separated into the following categories:
SGML Editing and Publishing includes traditional SGML
SGML Conversions is one of the largest sectors in the market
today because many companies are converting legacy data from
mainframes, or documents created with mainstream word
processors, into SGML.
Electronic Delivery is widely regarded as the most compelling
reason companies are moving to SGML. Electronic delivery
enables users to retrieve information on-line using an
intelligent document viewer.
Document Management may one day drive a major part of the
overall SGML industry.
SGML Document Repositories is one of the cornerstone
technologies that will affect the progress of SGML as a data
standard.
Since 1998, almost all development in SGML has been focussed
on
XML - a simple (and therefore easier to understand and
implement) subset of SGML.
characters. [How are these related to
ISO 8859-1?].
SGML parsers are available from
["The SGML Handbook", Charles F. Goldfarb, Clarendon Press,
1991, ISBN 0198537379. (Full text of the ISO standard plus
extensive commentary and cross-referencing. Somewhat cheaper
than the ISO document)].
["SGML - The User's Guide to ISO 8879", J.M. Smith et al,
Ellis Harwood, 1988].
[Example of some SGML?]
(2000-05-31)