/*REXX program shows how to  simultaneously  loop over  multiple arrays.*/
x. = ' ';      x.1 =  "a";      x.2 = 'b';      x.3 = "c"
y. = ' ';      y.1 =  "A";      y.2 = 'B';      y.3 = "C"
z. = ' ';      z.1 =  "1";      z.2 = '2';      z.3 = "3"

           do j=1  until output=''
           output = x.j || y.j || z.j
           say output
           end    /*j*/                /*stick a fork in it, we're done.*/