The menu of this option is extremely simple:
Choose an option:
1. Check position in the cell
Co. Show current atomic positions in fractional/Cartesian
------------ s e t t i n g -------------
An. [For input] Position is specified in: <Fractional>
Pr. Precision while checking position on equivalence: 1.0D-004
Q. Leave
-----> Choose the appropriate option:
When choosing position in the cell (in the representation controlled by An) in option 1, it will be checked agains existing atomic positions so that you would know if it is unique within some tolerance from Pr.