If you are not sure whether or not the book is an Annex item, look up the item record using the Item Display wizard and check the location.
Confirm with the patron that s/he is completely done with the book and it can be sent back to the Annex.
Discharge the item
Observe message "route to annex"
Mark through "TO DIV" on the paper wrapper and write "To : Annex"
Place item in the outgoing mail tray behind circ