To Add a Menu Mark to an Explorer Context Menu Item

In the Customize dialog ( File > Settings > Configuration > Customize ) on the Tools tab, expand the Explorer Context Menus tab.
Expand the open DGN library.
Select the context menu item to which you want to add a menu mark.
(Optional) If the Menu Mark Expression property is not visible on the General Settings tab, right-click the tab and select Add Menu Mark Expression.
Click the Menu Mark Expression drop-down.
A dialog with fields similar to the Named Expressions dialog opens.
Do one of the following:

In the Name drop-down list, select the named expression.

or
In the Name drop-down list, select Inline expression.
1. If you selected Inline expression, in the Symbol Sets selection drop-down list, select a symbol set and click Add.
2. In the Expression text box enter the value for the menu mark.
(Optional) Click Test.
If you selected the named expression, depending on the value returned by the expression, True or False is displayed in the field next to the Test button. If you selected Inline expression, the value is displayed in the field next to the Test button.
Click OK.
If you selected the named expression and the expression returns True, a menu mark is added to the context menu item. If you selected Inline expression, a menu mark is added to the context menu item.