touchmark

Noun

 * 1)  The manufacturer's official identifying sign, impressed into a pewter object.
 * 2) * 1988 Dec. 1, Susan G. Sawyer, Photog Pewter the Time-Honored Way," New York Times (retrieved 5 July 2012) :
 * For quality control, Parliament in 1503 required all London-made pewter to be stamped with the maker's symbol or touchmark.
 * 1)  A symbol, sign, or other inscribed indication used to aid the alignment, calibration, or other adjustment of a measuring device or scientific instrument.