Bundled with PROJ comes a set of small command line utilities. The proj program is limited to converting between geographic and projection coordinates within one datum. The cs2cs program operates similarly, but allows translation between any pair of definable coordinate systems, including support for datum transformation. The geod program provides the ability to do geodesic (great circle) computations. gie is the program used for regression tests in PROJ. cct, a 4D equivalent to the proj program, performs transformation coordinate systems on a set of input points. projinfo performs queries for geodetic objects and coordinate operations.