In the Administrator Message Console, when an ArcMap Service is created using a map with an unknown coordinate system the following error message may appear:
ArcIMS 4.0, 4.0.1:
"Coordinate system for the dataframe Layers is unknown"
"[WRN0509]Coordinate system for dataframe Layers is unknown."
The service is created but there may be limitations. It may not be possible to identify or select features. Also, formatted text saved in a geodatabase may be incorrect.
ArcGIS robustly handles ArcMap documents that are not in a known coordinate system. However, ArcMap Server is not as robust. Serving maps without a known coordinate system will limit client functionality. Clients viewing such services will be unable to identify or select features.