Initially used as a verb, meaning to imprint or impress, that is, to stamp a design. Straight-edge stamps have no perforations on one or two adjacent sides. Sometimes straight-edge stamps show a guideline. An overprint that changes or restates the denomination of a stamp. Paper colored on the surface only, with a white or uncolored back.
Humidity softens the gum, allowing separation of stamps.
Handstamped on a stamp, the T indicates the stamp's use as a postage due. Handstamped on a cover, it indicates that postage due has been charged. Several countries have used regular stamps with a perforated initial T as postage dues. This may be lines, bars, letters, part of the design area or the entire stamp surface. Some stamps are issued both with and without tagging.