Grid Domain
A grid domain is a two-dimensional domain unit, each cell is defined by a row and a column number.
This implies the value type of the domain is of type PointGroup.
Most grid domains in the GeoDMS are used to describe a part of the world, called geographic grid domains.
Furthermore, grid domains are also in use to define kernels for potential calcualtions.
Most functions in the GeoDMS work on data items of one (table) of two (grid) dimensional domains.
There is group of functions that explicitly use the two-dimensional structure of grid domains, for instance to calculate nearby relations. This group is called grid functions.
