AO-B2, 2002, Heroes of 2001, New York City, Add-on Cachet, FDC, 9-11, Firefighters Raising Flag at Ground Zero SC B2
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.