Complex sentence: A reverse index would store these in reverse order, thus "000000001-OS", "100000001-OS", "200000001-OS", and so forth, allowing the highly-variable last character in the column to scatter the values.
Split into simpler sentences: A reverse index would store these in reverse order, thus "000000001-OS", "100000001-OS", "200000001-OS", and so forth. The reverse index allows the highly-variable last character in the column to scatter the values.