Is the VBA example code for Check Digits broken?

from this page https://wiki.openmrs.org/display/docs/Check+Digit+Algorithm.

I copy the VBA code but it seems there is one issue at line 5.

For i = Len(ucIdWithoutCheckdigit) To 1 Step -2

I do not sure the -2 is an invalid syntax or incorrect logic. Could someone help me please? Thank you