Custom Functions

I'm working at a responsive template based on Zurb Foundation and I have some custom functions . In practice I have to create my own zen_draw_form() function and others but I don't want to make changes on /include/functions/html_output.php file cause I don't like the idea to change core files .
I ask you where is better to place my custom functions files ( used only for new template ) in order to keep clean the core files .

THANK YOU

Functions can't be overwridden, which means that there are a very limited number of places whereby you can define your own without causing a conflict. I see no reason why you can't define your custom function(s) within the template file itself. If you prefer to store them in a more 'global' location you'll need to take steps avoid any conflict with the original functions.. The easiest way to do this is to call your functions by a slightly different name than the originals. Your newly created functions can then simply be placed in a file in your /includes/functions/extra_functions/ folder.

Cheers
Rod

Sorry Rod , but my english is a mess ..
I did not plan to overwrite functions but to create new functions ( different names ) without modify core files . You gave me the solution by placing my custom file inside /includes/functions/extra_functions/ .

Thank you