a small movable auxiliary scale, attached to, and sliding in contact with, a scale of graduation. Usually graduated at 9/10 of the scale on the main scale, it enables readings on the latter to be made to a fraction (usually a tenth) of a division by noting which member of the auxiliary scale is aligned with any line on the main scale., nihikutes, optikariistades jm. kasutatav abiskaala mõõteriista põhiskaala jaotiste murdosade lugemiseks