- Preprocessors are also used for providing template suggestions.
- In versions 5 and below, the function _phptemplate_variables served the same purpose. It has been deprecated in 6.
- Prior to Drupal 6.7, for your theme to have its preprocessors recognized, the template associated with the hook had to exist inside the theme. When a default template exists, copy it to your theme and clear the registry (or you should really be upgrading to a later version of Drupal anyway for security reasons, at which point you don't have to worry about this).