Backward Compatibility for User Defined Datums with Grid Shift Files
Support for a custom GCS with user defined Datums using Grid Shift file is introduced in Update 16. The GCS is retained in the DGN model and can be seen; however, datum conversion is not possible.
When loaded in a previous version of
OpenBuildings Speedikon the GCS will be loaded but
will appear flawed irrespective of whether the user library available:
Note: A user library containing user-defined datums using grid shift files
can be read by previous versions of MicroStation and all datum not based on
grid shift files remain available. In older versions of MicroStation, however,
the Grid Shift file-based user datum can be edited but not renamed.
Although the datum can be read, the grid file definition cannot be
loaded in versions prior to Update16. This implies that when performing
reprojection no datum conversion will occur and a warning message may appear in
the Message Center:
As a general rule, versions prior
to Update 16 should not be used if possible, and if they are, it should not
imply reprojection.