This is both a plaintext formatting syntax, and a
Perl script that converts it to
XHTML. The objective was that the
souce file should not look like markup (so it could be
read just as a plaintext document), but that it should
be sufficiently robust to withstand conversion.
Details are at http://daringfireball.net/projects/markdown/.
There are several of these: the best-known is
probably the MediaWiki format used by Wikipedia,
which provides fairly extensive plaintext facilities
for creating the entries used in the site, which are
then converted to HTML for
Similar conceptual formats are used by some other
wiki systems such as PmWiki
Code; and there are hybrids which also use
HTML like Fossil.
The LATEX document-preparation and typesetting
system (Lamport, 1994) uses macros
built on TEX syntax to implement a
partially-structured document model. The syntax uses
the backslash to flag markup elements and formatting
instructions, and curly braces to delimit arguments
and restrict the scope of typographic actions.
The software is available on all platforms, and
creates PDF or PostScript output.
Conversion into LATEX from
XML-based systems can be done with
XSLT, but conversion out of LATEX
syntax is problematic because it has features not
easily representable in other systems.
SGML and some of its
progenitors remain available but are rarely