U+2400 "␀" Symbol for Null Unicode Character

U+2400 "␀" Symbol for Null is a graphic representation of the ASCII control character NUL, which has a code point of 0 in the ASCII standard. It is typically depicted as the letters "NUL" enclosed within a rounded rectangle or bubble, a design intended for use in control character pictures or circuit diagrams to visually indicate a null value or empty state. This symbol belongs to the Control Pictures block of Unicode, which was created to provide visible icons for nonprinting control characters used in telecommunication and data transmission protocols.