Functions internal to a class implementation

I have a class for elements of an HTML form and a bunch of subclasses for text box, radio, etc. I need some utility functions which will be called by some of the subclass implementations. These are utilities used within the class only, they are not methods. Is there a "best" way to implement this given that there are no private functions in PHP? The options seem to be to define the utilities globally, or define them as methods in the superclass and call them with superclass::func(); in either case I would never call them externally. Thanks for any tips, ---------- Tom Rawson