30:35 · This ideogram is found both in earlier and present-day systems. In the earliest system of Chinese writing the similar meant village (a pictorial sign for the central field and well).
    In alchemy meant urine. As a meteorological sign signifies that the ground is wet ( means flooded ground).
    Placed diagonally, it was sometimes used by alchemists to mean sulphur although it was more usual to represent sulphur with or .
    In the French and US system of hobo signs and similar structures are signs for danger. See, for example, , this water is dangerous to drink; , dangerous neighborhood; and , here lives a man with a bad temper.
    In some fire protection contexts it has signified the whereabouts of a police station. In military contexts has been used for vehicle driver, and for orderly.