Coordsys.db

From Fmepedia

The coordsys.db file in the FME install directory is just a set of names that the FME user interface lets users pick from. It is typically a subset of all the definitions that are known to FME (i.e. there may be some additional systems defined in the coordsys file that aren't in the coordsys.db either because the systems have been deprecated, or some other reason).

Any systems defined in LocalCoordSysDefs.fme, MyCoordSysDefs.fme or as an FME Shared Resource are automatically added to the GUI as well and don't need an entry in this file.