Special Features:

Luminous legend; illumination as the result of activation of a phoshor by the radioactive particle emissions of tritium gas with in sealed transparent tubes

Properties:

An object for the display of information, instruction, warning, or direction, by means of words, symbols, colors, or shapes. May be luminous or reflective, but shall not be internally illuminated. Excludes sign, interior illuminated, electric. for self-illuminous items, see marker, self-luminous.