*!* Swap two variables
 LOCAL a, b
 a = 1
 b = "Hallo"
 ? a, b
 *!* Pass a and b by reference
 Swap(@a, @b)
 ? a, b

PROCEDURE Swap(v1, v2)
LOCAL dum
dum = v1
v1 = v2
v2 = dum
ENDPROC