SGML is the Standard Generalized Markup Language.  SGML is defined
in International Standard ISO 8879:1986.  SGML is a language for
formally describing the structure and contents of documents.  SGML
is also the syntax used by documents so described.

SGML is an important move in the direction of separating information
from its presentation, e.g. making different presentations possible
for the same information.  The better macro packages for TeX and
troff attempt to do the same thing.  This is in contrast with WYSIWYG -
see GN5.

SGML is more fully discussed in comp.text.sgml.

SGML is the name of a directory at the public FTP site ftp.ifi.uio.no
where you can find a (draft) FAQ, a bibliography, and more information.

ODA: Office [Open] Document Architecture, takes a similar approach
but stresses blind interchange.  ODA is defined in the multi-part
standard ISO 8613:1988, in the CCITT T.410 series recommendations,
and in ECMA standard 101.