Tasks are defined in package.xml through the tasks namespace, which is currently http://pear.php.net/dtd/tasks-1.0. The current tasks namespace is defined by http://pear.php.net/dtd/tasks-1.0.xsd. Custom tasks bundled with PEAR include:

• <tasks:replace>

• <tasks:unixeol>

• <tasks:windowseol>

• <tasks:postinstallscript>

The xml for each of these tasks is documented here.