REXX allows it to redefine any built-in function in a REXX program. If, for example, you define a function named DATE in your program the call
curDate = date()
calls your newly defined function and NOT the built-in function date()
To call the built-in function -- for example in your new defined function -- call it like this:
call "DATE"
or
curDate = "DATE"()
Important: You must use the name of the built-in function in uppercase!
Note: See Expand the function FILESPEC, Check if a queue exists, or Call by value for working examples.