for loop usage of "by"

[Anonymous]

array1 = #("A", "B", "C")
array2 = #()
array3 = #()

--copying the array
array2 = for idx in array1 collect idx
--reversing the array
for idx = array1.count to 1 by -1 do (append array3 array1[idx])

In the above segment I looked in the reference manual for a maxscript for loop however I didn't get a very detailed explanation of what happens when the "by" operator is used? What does "by -1" mean? Could I get a detailed explanation of this usage please?

Thank You!

[Swordslayer · Accepted solution]

Iterator increment, if you don't want to increment by one.