Groupwise.DisplayAddressBook() is a wrapper of the GroupWise ActiveX* Address Book Control. GroupWise® Controls for ActiveX* contains two address book controls: Name Completion Control and the Address Book Control.
Unfortunately, the Address Book control does not have any properties/methods which lets you to decide the target type (i.e. TO, CC or BC) of the address selected. However, it can return the total entries of a specified target type. For example:
msgbox "Target Type All: " & MainDlg.gwAB.TargetType(0)
msgbox "Target Type TO: " & MainDlg.gwAB.TargetType(1)
msgbox "Target Type CC: " & MainDlg.gwAB.TargetType(2)