42:2 · The Egyptians used as a cartouche, that is a hieroglyph surrounding other hieroglyphs. (On some Egyptian grave paintings the sign sometimes occurs as , the Greek sign omega.)
    In the Australian designer Bliss' system was used to mean day. Bliss used the same structure, but turned upside down, to denote night.
    As a modern military sign it is used to denote an outpost.