The PHP 4 documentation was removed from the PHP Manual in August 2014, approximately six years after PHP 4 reached its end of life. However, we have provided downloadable copies of the manual for anyone who would need it, as well as a link to a hosted third-party version.
An attempt has been made to preserve as much documentation related to PHP 4 as possible. Despite this, we don't have a nice, separate manual covering only PHP 4. The reason for this is how our documentation is structured. Even so, the linked copies describe more aspects of PHP 4 than the actual manual described in August 2014 (e.g. it covers more PHP 4 extensions).
Please remember that these documentation versions should not be used in everyday development, unless you are maintaining PHP 4 applications. These versions lacks many topics connected with newer PHP versions and are not updated anymore.
All users are strongly encouraged to upgrade their environments to newest PHP version. Please read our guides for Migrating from PHP 4 to PHP 5.0.x for more information.