A pattern of characters used to control the retention or elimination of portions of another pattern of characters. Also known as extractor.

A frame used in front of a television picture tube to conceal the rounded edges of the screen.

A thin sheet of metal or other material containing an open pattern, used to shield selected portions of a semiconductor or other surface during a deposition process.

A protective covering for the face or head in the form of a wire screen, a metal shield, or a respirator.

1. In color separation photography, an intermediate negative or positive that is used to correct color.

2. In offset lithography, opaque material that protectively covers open or selected areas of a printing plate during the exposure process.

A protective device in thermal spraying against blasting or coating effects which are reflected from the substrate surface.