The for operator implements a counting loop. This operator takes three integers and one executable array:
   i0  d  i1  { ops } for
i0 is the loop counter's starting value, d is the increment amount, i1 is the final value. The for operator put the value of the counter on the stack before each execution of ops. For example, the program line
  1 1 5  { /i set i message } for
   1  2   3   4   5

Nobuki Takayama 2020-11-24