Answer
EPSG stands for European Petroleum Survey Group. They publish a database of coordinate system information plus some very good related documents on map projections and datums. The Projection Engine uses a modified version of the EPSG model.
POSC is the Petrotechnical Open Software Corporation. It publishes open standards for the energy and petroleum industry. The POSC standard uses the EPSG model.
Article ID:000002814
Software:
- Legacy Products
- ArcMap 8 x