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.
CDuce is a programming language adapted to writing safe and efficient applications that manipulate XML documents. A type system checks at compile time that applications deal with all the possible inputs and produce only valid outputs. Pattern matching is a powerful operation based on regular expressions to inspect documents. CDuce also features general-purpose features; it is a higher-order functional language, with a type-safe interface with Objective Caml.
xcb-proto contains descriptions of the X Window System core protocol and selected extensions in an XML-based data format. They are used by the X C Binding (XCB) library to generate much of its code, but you can also use these descriptions for other purposes, such as decoding the X protocol or building X Window System bindings for other languages.
The XCB library provides an interface to the X Window System protocol, designed to replace the Xlib interface. It has several advantages over Xlib, including size (small library and lower memory footprint), latency hiding (batch several requests and wait for the replies later), direct protocol access (one-to-one mapping between interface and protocol), thread support (access XCB from multiple threads, with no explicit locking), and easy creation of new extensions (automatically generates its interface from machine-parsable XML protocol descriptions). Xlib can also use XCB as a transport layer, allowing software to make requests and receive responses with both, which eases porting to XCB. However, client programs, libraries, and toolkits will gain the most benefit from a native XCB port.