Print-on-Demand means simply that the comics you order are printed as you order them. They are not stacked on shelves or stored in longboxes waiting to be shipped out. They literally do not exist until they are ordered.
This means there is no first printing or second printing, etc. The print run on a print-on-demand comic is open-ended and unlimited. If the printable document remains unchanged, then a comic printed here ten years ago would be identical to and indistinguishable from that same comic printed today.
The IndyPlanet catalog consists of many terabytes of printable document files stored in archives on the cloud. When you place an order, we access the corresponding printable document from the archive and send it to press. A few seconds later your printed comic rolls off of a conveyor belt at the end of the press and is packed and shipped.