Question

When I create a custom coordinate system do I have to define it in coordsys.db?

Answer

Coordsys.db contains a set of coordinate system names that the FME user interface lets users pick from.

Any coordinate system defined in MyCoordSysDefs.fme, LocalCoordSysDefs.fme or as an FME Shared Resource is automatically added to this file (and thereby to the FME GUI) and doesn't need an explicit entry in the coordsys.db file in the FME install directory.

See the Coordinate System documentation for information on defining custom coordinate systems and how to add then to your FME install.