ACEO stand's for  ART CARDS EDITIONS and ORIGINALS  which are traded and sold through various ways. There are many on Ebay and there are sites where you can see them.  They must be 2 1/2"  X  3 1/2"  to be an ACEO.  The one's here were painting in Germany.  These may all be bought as a signed  print for $8.00 each.  Purchase through Paypal under  artwithlove@sbcglobal.net  To let me know which one, count to the one you want. Sorry, that's the best I can do at the moment.