This manual is written in XML using the DocBook XML DTD, using XSLT (Extensible Stylesheet Language Transformations) for maintenance and formatting.
Using XML as a source format gives the ability to generate many output formats from the source files, while only maintaining one source document for all formats. The tools used for formatting the online manual are xsltproc and DocBook XSL Stylesheets. The HTML and TeX versions use Jade, written by James Clark; and The Modular DocBook Stylesheets, written by Norman Walsh. We use Microsoft HTML Help Workshop to generate the Windows HTML Help format of the manual, and of course PHP itself to do some additional conversions and formatting.
The PHP manual is generated in various languages and formats, see http://www.php.net/docs.php for additional details. The XML source code may be downloaded from CVS and viewed at http://cvs.php.net/. The documentation is stored in the phpdoc module.