SGML is
an acronym for "Standard Generalized Markup Language," an
international standard for representing information. The term
"markup" comes from the publishing world, originally referring to the
instructions that an editor would give to a typesetter when producing a printed
text from a manuscript. Today we use "markup" to mean the instructions
that accompany an electronic text. Unlike traditional markup instructions from
editor to typesetter, which had primarily to do with the way the text would
appear on the printed page, SGML is used principally to convey information
about the function and content of the text rather than its appearance.
Why is this important? Although computers are very powerful in certain
ways, they have no ability to interpret text the way the human mind does. We
can look at four documents and understand that the first is a personal letter,
the second a prescription for medicine, the third a bank statement, and the
fourth a multiple-choice quiz. Similarly, when we read the personal letter, we
can tell that the writer is using a phrase ironically or inserting a quotation
in a foreign language. Computers can't make judgements like this unless we add
descriptive information in a systematic way, and that's
Extensible
Style Language (XSL) is used to transform XML files into other types of
documents. An XSL stylesheet can, for example, facilitate the creation of an
HTML display of a source XML file.
If you're
interested in learning more about SGML, the web page contains a collection of
introductory essays:
