What is the ‘Reference’ mean in Trace & Reference?

It means you can copy any item/objects (with all the associated metadata / properties) and place it on the current View Map (window) you are in without having to change View Maps.

• Turn ‘Trace & Reference’ on from any View Map or Layout Book you wish where you want to copy an item/object.
• Use ‘Eye Dropper’ (Alt+C). This will copy that item/object in the current View Map you are in.