OpenCities Map has the ability to open and display the contents of a MicroStation design file as if they were features. This is done through a mechanism called Dynamic Feature Scoring (DFS) which identifies or flags elements as features without actually making changes to the elements. This makes non-feature (MicroStation) data available for use with Bentley Map, but sit also increases the time it takes to open a design file.
DFS is on by default and results in the words "Inferred Feature" when you hover your mouse over an element. To turn DFS off, set MS_GEOXFM_NO_DYNAMICSCOREDFEATURES = 1. The element is then identified the same as MicroStation.
Note that enabling this variable will inhibit some OpenCities Map functionality, specifically the export tool in the Interoperability dialog, the Map Manager, the Data Browser, or publish the elements for Bentley Map Mobile. In order to use those parts of Bentley Map, the elements need to be seen as features.