If I'm saving two cubes in a CubeList both with a coordinate with a var_name of 'dim_0', one will be incremented in the resulting file to 'dim_1'. This might be confusing if it relates to the zeroth dimension. Furthermore what if my names are 'dim_0', 'dim_1', ...? Incrementing will occur when saving the second cube, but you'll still have a conflict as 'dim_1' will be taken.