Hors Commerce (H.C.)
Translated from French as "Not to sell," publishers use such impressions as exhibition copies, thereby preserving the numbered impressions from overexposure or rough handling. These proofs started to appear on the market as extensions of editions printed in the late 1960's. They may differ from the edition by being printed on a different kind of paper or with a variant inking; however, they may also not differ at all.