The Equidistant Cylindrical projection (also called the Equirectangular projection, geographic projection, Plate Carrée, or Carte Parallelogrammatique projection or CPP), is a very simple map projection attributed to Marinus of Tyre, who Ptolemy claims invented the projection about 100 AD.
The projection maps meridians to equally spaced vertical straight lines, and circles of latitude to evenly spread horizontal straight lines. The projection is neither equal area nor conformal. Because of the distortions introduced by this projection, it has little use in navigation or cadastral mapping, and finds its main use in thematic mapping. In particular, the Plate Carrée is used often in computer applications that process global maps, because of the particularly simple relationship between the position of an image pixel on the map and its corresponding geographic location on Earth. The Plate Carrée (French, for "flat square"), is the special case where standard parallel is zero.
The following examples are of PRJ entries for Plate Carrée and Equidistant Cylindrical projection centered at 46.5 degree Standard Parallel (used in France):
"Plate Carree WGS84", 33, 104, 7, 0, 0, 0, 0
"Equidistant Cylindrical 46.5 Degree WGS84", 33, 104, 7, 0, 46.5, 0, 0