Where does theme($row) get evaluated?
This is a method call, the theme method is invoked on the $view-&gt;field[$id] object. The method is likely views_handler_field::theme but it may have been overrided by the  views_handler_field subclass used for a particular field handler. Usually, the method will eventually ends up calling the theme() function to use a defined theme function or template for the field (if this is a CCK field, a formatter will likely be used).