WKT (Well Known Text)

WKT (Well-Known Text) is an OGC standard text encoding for geometry and for coordinate reference systems. The geometry form describes features such as POINT, LINESTRING, and POLYGON in plain text for storage and exchange. The CRS form, defined in ISO 19162, spells out a coordinate system as nested keywords: datum, ellipsoid (semi-major axis and inverse flattening), prime meridian, projection method, parameters, and units. WKT and EPSG codes are the two interchangeable ways GIS and hydrographic software carry a CRS definition; WKT is self-contained where an EPSG code is a lookup. A WKT2 revision aligns the CRS grammar with the modern geodetic model.