PostgreSQL has four primary documentation
  formats:
  
-      Plain text, for pre-installation information
     
-      HTML, for on-line browsing and reference
     
-      Postscript, for printing
     
-      man pages, for quick reference.
     
  Additionally, a number of plain-text README-type files can be found
  throughout the PostgreSQL source tree,
  documenting various implementation issues.
 
  The documentation is organized into several "books":
  
-      Tutorial:  introduction for new users
     
-      User's Guide: documents the SQL implementation
     
-      Reference Manual: reference pages for programs and SQL commands
     
-      Administrator's Guide: installation and server maintenance
     
-      Programmer's Guide: programming client
     applications and server extensions
     
-      Developer's Guide: assorted information
     for developers of PostgreSQL proper
     
  All books are available as HTML and Postscript.  The
  Reference Manual contains reference entries which
  are also shipped as man pages.
 
  HTML documentation and man pages are part of a
  standard distribution and are installed by default.  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 document style defines how that
   content is rendered into one of several final forms.  DocBook is
   maintained by the OASIS group.  The official DocBook
   site has good introductory and reference documentation and
   a complete O'Reilly book for your online reading pleasure.  The
   FreeBSD
   Documentation Project also uses DocBook and has some good
   information, including a number of style guidelines that might be
   worth considering.