AO-4084i-1, 2006, DC Comics Super Heroes, Supergirl, FDC, Add-on Cachet. Digital Color Postmark, SC 4084i

Add-on cachet is:

A cachet design added to a cover which was originally uncacheted. An add-on cachet should be identified

by maker and date (mine are stamped on the back with the date) so that it is clear that it is not contemporary with the cover.