Note: Alternatively, select a door/window assembly in the drawing, and click Door/Window Assembly tabGeneral panelEdit Style drop-downDoor/Window Assembly Styles.
Select a door/window assembly style.
Click the Design Rules tab.
In the left pane, select the grid in which you want to create a new mullion assignment.
Click (new mullion assignment).
A new mullion assignment is displayed in the list of mullion assignments.
Right-click the default name, click Rename, and then enter a descriptive name.