The following discusses adding a new datum or ellipsoid. This functionality is only available in Bentley Map SELECTseries 3 or later. It is not found in MicroStation.
Locate, copy and rename the delivered ...\MapEnterprise\coordinate\seed\seed.dty file to a folder and name of your choice. If this file is to be shared among users, consider placing it in your Standards folder. For example: ...\WorkSpace\Standards\coordinates\CustomGCS.dty
In your project schema, or other configuration file such as your standards.cfg, create the variable MS_GEOCOORDINATE_USERLIBRARIES = Library[Name]. The Library is the name and location of your dty file. The Name is the name of the root node in the Select Geographic Coordinate System dialog. If [Name] is omitted, the file name will be used.
For example: MS_GEOCOORDINATE_USERLIBRARIES = $(_USTN_SITE)/coordinates/CustomGCS[Custom GCS]
To verify that the variable is being read, start Bentley Map and open the Select Geographic Coordinate System dialog. Your newly defined node should be visible.
For multiple folders, separate the files with a semi colon.
MS_GEOCOORDINATE_USERLIBRARIES = $(_USTN_SITE)/coordinates/CustomGCS.dty[Custom GCS];$(_USTN_SITE)/coordinates/ProjectABC.dty[Project ABC]
To add a new ellipsoid: Select Edit Ellipsoids > New to create a new ellipsoid.
Edit the parameters as required.
To add a new datum: Right-click on the new folder and select Edit Datums > New and set the parameters for the datum.
A datum requires an ellipsoid.
The available ellipsoids are those that are in the same user library and those that are in the system library.
The user library ellipsoids will be at the top of the list.
To add a new geographic coordinate system: Select an existing coordinate system from the delivered library, right click and select Copy.
Navigate to your custom folder, and paste.
Once pasted, you can edit the properties as needed:
Note that custom datums will be available from the dropdown list:
Changes cannot be read by Bentley Map SELECTseries2 or older.
If you want to provide your Geographic Coordinate System information, including your personal datum and/or ellipsoid, you will only need to provide the customized dty file.
For more details, please refer to:
Editing Coordinate Systems