This manual is written in XML using the DocBook XML DTD, using DSSSL (Document Style and Semantics Specification Language) for formatting. The tools used for formatting HTML, TeX and RTF versions are Jade, written by James Clark and The Modular DocBook Stylesheets written by Norman Walsh. PHP's documentation framework is maintained by Stig Sæther Bakken.
You can download the manual in various languages and formats, including PDF, plain text, plain HTML, WinHelp, and RTF from http://www.php.net/docs.php.
Daily HTML snapshots of the manual, including translations, can be found at http://snaps.php.net/manual/.
You can find more information about downloading the XML source code of this documentation at http://cvs.php.net/. The documentation is stored in the phpdoc module.