3. The apparatus of claim 1 wherein the self-inking printing device includes an elastomeric foam substrate material impregnated with a printing ink and faced with a selectively-permeable outer membrane so as to form a character segment when pressed against the document.
3. The apparatus of claim 1 wherein the self-inking printing device includes an elastomeric foam substrate material impregnated with a printing ink and faced with a selectively-permeable outer membrane so as to form a character segment when pressed against the document. 4. The apparatus of claim 3 wherein the self-inking printing device comprises a cylindrical, self-inking print roller.