where is the DIR directive defined

[Frank H. Shaw]

I have been looking and can not locate where the DIR directove is defined as in the following example peice of code:

PHP Code:


     require_once(DIR . '/includes/functions_calendar.php'); 


I want to use the DIR goblal varable in my custon php mod and can not find it in the vb code - I do have some troubles with my eye site and it might be me - a little explation on the use and where abouts this is defined would help me figure some things out.

THANKS

Frank H. Shaw