The sgml-common package gathers very basic stuff necessary to work with SGML and XML, such as xml.dcl, a SGML declaration of XML; iso-entities, a list of the basic SGML ISO entities; and install-catalog, a script used to add entries to (or remove entries from) centralized catalogs whose entries are pointers to SGML open catalogs, as defined by OASIS. It also includes sgmlwhich, a small script which prints where the SGML main configuration file is located (provided for compatibility with non-FHS systems).
DocBook is an XML vocabulary which enables you to create document content in a presentation-neutral form that captures the logical structure of the content. Using the DocBook Project XSL stylesheets, you can publish DocBook content as HTML pages and PDF files and other formats, including man pages, HTML Help, and JavaHelp.
MagicHat is a programmer's research and reference tool. With MagicHat, you can navigate through a Cocoa's application programming interface (API), review the declarations of language elements such as methods, functions, and constants, and retrieve relevant passages from the Cocoa developer documentation. MagicHat helps you unravel unfamiliar code, whether building blocks from the Cocoa software kits, programming examples, or programs written by your own development team.