A custom coordinate system is a Shared Resource that defines one or more coordinate systems that are not included in FME by default.
FME is used in many different countries around the world, and it is also used with a variety of custom datasets within each country. However, sometimes FME’s Coordinate System Gallery doesn't include the coordinate systems that are being used. In these cases, you will have to define the coordinate systems before FME can use them.
coordsys.db in the FME installation directory contains the names and descriptions
of all predefined coordinate systems. It is typically a subset of all
the definitions that are known to FME (that is, 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 FME and don't need an entry in this
file. LocalCoordSysDefs.fme,
and resides in the Reproject subdirectory under the FME installation directory.
It contains a series of COORDINATE_SYSTEM_DEF,
DATUM_DEF, ELLIPSOID_DEF, and UNIT_DEF lines that define additional, site-specific
coordinate systems. You can edit these files to add your own definitions.LocalCoordSysDefs.fme is a file that contains
overrides to the standard coordinate systems (and related parameters)
defined by FME. The built-in definitions for any coordinate system/datum/ellipsoid
may be overridden if by a text defintion in the Reproject/LocalCoordSysDefs.fme
file. FME ships with a number of overrides (and supplemental) systems
in this file. The structure of LocalCoordSysDefs.fme is the same as the
custom coordinate system file MyCoordSysDefs.fme,
and its contents can be used as a template for new custom coordinate systems. You should NOT edit LocalCoordSysDefs.fme,
because each time FME is installed, it will overwrite this file with whatever
is current for that version of FME.
MyCoordSysDefs.fme
in the Reproject directory contains custom coordinate system definitions.WARNING: Although FME does not overwrite MyCoordSysDefs.fme during
installation, it is always good practice to back up the file anyway. In
addition, although you should not have to edit either the LocalCoordSysDefs.fme
and coordsys.db files, FME overwrites these files during installation.
Therefore, you will have to back up the files if you have made any changes.