The following code shows the use of optimized subscripts:
01 a pic xx occurs 10.
01 b pic xx occurs 10.
01 c pic xx occurs 10.
01 d pic xx occurs 10.
...
move a(i) to b(i)
if c(i) = d(i)
display "pass"
end if
The result would be that the subscript i would be evaluated only once, although it is used four times in two statements. The stride of each of these tables is the same: two.