Level Manager dialog
Used to control level display and level symbology for the open DGN/DWG file and attached references.
By default, the Level Manager includes a list of models, levels, and filters on the left, and a detail section on the right.
You can select multiple design files and/or reference attachments from the tree by holding the left mouse button down and dragging the cursor over the desired files. The levels for all the selected files display in the level list.