There are many notices of the 'Undefined' variable variety. These mask real warnings about real bugs, hampering quality control.
These warnings are currently so numerous as to be unwieldy and must be shut off on development platforms via the following setting in php.ini:
error_reporting = E_ALL & ~E_DEPRECATED& ~E_NOTICE
However, server/compiler warnings are useful for quality control and should never be ignored, so developers should instead be using the following setting:
error_reporting = E_ALL | E_STRICT
To facilitate the setting above, current warnings should each be tracked down and fixed and new warnings addressed as they arise.