PostgreSQL has four primary documentation formats: Plain text,
for pre-installation information HTML, for on-line browsing and
reference PDF or Postscript, for printing man pages, for quick
reference. Additionally, a number of plain-text README files can
be found throughout the PostgreSQL source tree, documenting
various implementation issues. HTML documentation and man pages
are part of a standard distribution and are installed by
default. PDF and Postscript format documentation is available
separately for download. The documentation sources are written
in DocBook, which is a markup language superficially similar to
HTML. Both of these languages are applications of the Standard
Generalized Markup Language, SGML, which is essentially a
language for describing other languages. In what follows, the
terms DocBook and SGML are both used, but technically they are
not interchangeable. DocBook allows an author to specify the
structure and content of a technical document without worrying
about presentation details. A