4.17.1. A Simple User Function4.17.2. Return Values4.17.3. Parameters4.17.4. Passing By Reference4.17.5. Returning by Reference4.17.6. Default Parameters4.17.7. Variable Parameter Counts4.17.8. Variable Scope in Functions4.17.9. Overriding Scope with the GLOBALS Array4.17.10. Recursive Functions