To Attach a Model as a Reference Residing in a Directory Specified by a Configuration Variable

In the References dialog ( Drawing > Attach > References dialog launcher ), click the Attach Reference icon.

The Attach Reference dialog opens. Even if the model you want to attach is displayed in the Files list box, do not skip steps 3-4.
In the icon menu bar, click the Directory History icon (far right) and, from the drop-down menu, choose Select Configuration Variable.
The Select Configuration Variable dialog opens.
From the list box, select the configuration variable that specifies the directory in which the DGN resides (for example, MS_RFDIR), then click OK.
The Attach Reference dialog lists files in the specified directory.
From the list box, select the file to attach and click OK.
The Reference Attachment Properties dialog opens.
Select the required model, adjust other settings as necessary, then click OK.
The configuration variable name is stored, along with the filename, (optional) logical name and (optional) description, in the attachment information.

OpenCities Map will locate a model attached in this manner whenever the DGN file is opened — on any system — as long as the custom configuration variable is defined and the DGN file that contains the model is stored in the specified directory. The specified directory can vary from system to system.