Migrating from PHP 5.2.x to PHP 5.3.x
PHP Manual

Backward Incompatible Changes

Although most existing PHP 5 code should work without changes, you should pay attention to the following backward incompatible changes:

The following keywords are now reserved and may not be used in function, class etc. names.


Migrating from PHP 5.2.x to PHP 5.3.x
PHP Manual