Z Reset Position - 1880 Seems a Strange Number

The normal setting for Z Reset Position is 1877, and as I understand it, the floor of the vat is at 1880. This seems to indicate that each increment of Z Reset Position would be 0.0957446808mm assuming a build height maximum of 180mm. That seems a little strange and I wonder if the build height is really 188mm making each increment .1mm?

Each increment is .100mm and the 180mm is available for build height.

Thanks. It is the only thing that makes sense but I thought that I would ask.

you also lose 0.1mm on z-axis print volume when you decrease z-reset position by 1.