A current practice of some artists is the addition of a small personalized drawing or symbol near his pencil signature in the lower margin. The practice is borrowed from Whister's famous 'butterfly' which was added to personalize many of his graphics. Found on http://www.encyclo.co.uk/local/21109
Re·marque' noun Also Remark (Engraving) (a) A small design etched on the margin of a plate and supposed to be removed after the earliest proofs have been taken; also, any feature distinguishing a particular stage of the plate. (b) A print or proof so distinguished; -- commo... Found on http://www.encyclo.co.uk/webster/R/47