1Datum is the dimensions of the ellipsoid, taken as a basis in the selected country, fixed at a certain time, taking into account the coefficients of displacement and rotation of the ellipsoid, which bring it into line with the selected country.
2Most SRSs will be either Geographic (using the Spherical coordinates of latitude and longitude) or Projected (including thousands of Cartesian coordinate systems, each based on a map projection to create a planar surface of the world or a region).
3WKT (Well-known text) - text format of a vector geometry representation and a description of a coordinate system designed to share spatial data between information resources and services.
