That grid square is 1km x 1km on typical maps, please don't leave it as a full grid during normal traffic. I do not feel like walking around the entire square to figure out what your talking about.
It depends on the game/interface. Squad/Arma/etc that use milsim as a selling point will stick to the trusty 1km x 1km scale for squares. These can be represented by the larger 12500 scale or down to the 500 scale, representing the nominal grids per map area. Each portion of the world (different by nation) is divided up and given its own identifier, UK/US/CAN use two letter combos for most of their maps except the poles where they use one number and one letter. This identifier is used for any asset such as artillery so they know what map to reference when coordinating a fire mission. This will generally already be done before you sp.
