I want to learn what is the distance unit on a navigation display.

[![http://www.viennaflight.at/ihr-airbus-a320-funflight/.][1]][1]

I pointed the distance marks with red circles on the navigation display. What are these 10, 15 etc. values' unit? Are they representing mile, nautical mile or kilometer?

And can it be adjusted in a different measurement unit (mile, kilometer or nautical mile) or is it a standard unit for aviation and navigation displays?


  [1]: https://i.sstatic.net/CP5Xv.jpg