A mark or token added to those already existing, in
   order to afford security or proof; as, an additional or special mark
   put upon a package of goods belonging to several persons, that it may
   not be opened except in the presence of all; a mark added to that of an
   artificer of gold or silver work by the Goldsmiths' Company of London,
   to attest the standard quality of the gold or silver; a mark added to
   an ancient coin or medal, to show either its change of value or that it
   was taken from an enemy.