You can edit a reference in-place from within the active model. To do this you first must temporarily activate the reference.

The reference cannot be activated if:

• The display of the reference is turned off.
• It is open for editing in another session.
• It is a perspective reference attachment.
• The visible edge option is set to Legacy.
• The reference orientation is Geographic Reprojected. However, the reference orientation Geographic AEC Transform can be activated.
• The master file is read only and the reference is to another model in the master file.
• The file format is anything other than V8 DGN, DWG, or DXF.

When a reference is activated:

• Only operations on the activated reference are permitted.
• By default, all elements in references above the activated reference in the file hierarchy, as well as the active model, are displayed with an override color. You can control whether or not an override color is used, and what the color is, with the Active Reference Override Color preference ( File > Settings > User > Preferences , Reference category).
• If you activate another reference, the currently activated reference is automatically deactivated.
• The reference is locked so that it cannot be edited in another session.
• DGN library data, such as levels and level filters, is not available in an activated reference file.

To return to editing the active model, you have to deactivate the reference.

References that have been activated are not available for editing in another session. This also applies to references that have been deactivated. To make a reference available for editing in another session, you must release the lock on it. You can do this automatically by exiting from the file or manually.