6C. endproc/return
As stated before, ENDPROC marks the end of a function definition, and may
return a value. Optionally RETURN may be used at any point in the function
to exit, if used in main(), it will exit the program.

RETURN [<returnvalue>]          /* optional */


PROC getresources()
  /* ... */
  IF error THEN RETURN FALSE  /* something went wrong, so exit and fail */
  /* ... */
ENDPROC TRUE   /* we got this far, so return TRUE */

a very short version of a function definition is:

PROC <label> ( <arg> , ... ) IS <exp>

("RETURN" instead of "IS" is allowed, but obsolete)
These are function definitions that only make small computations, like
faculty functions and the like:  (one-liners :-)

PROC fac(n) IS IF n=1 THEN 1 ELSE fac(n-1)*n