OpenCities Map supports the following geospatial feature types: points, line, and polygons. Dimensions, as we know them from the MicroStation world, are not supported feature types in OpenCities Map and result in a ? symbol in the Map Manager.
OpenCities Map can post and query features that contain the dimension values for X, Y, Z, length, area, volume, time, and other measurements for spatial data. This does not include graphic grouped geometry which is dynamically linked to text values such as dimension elements.
There would certainly be ways to store your OpenCities Map feature data in SQL Server Spatial while at the same time using Dimension tools in MicroStation for visualization. Combining multiple applications and application data is sometimes necessary to achieve the desired result.