A system of writing music for fretted instruments, most commonly the guitar, whereby a number or letter appears on lines representing the strings, indicating the fret to be played.
A six-line staff graphically represents the guitar fingerboard, with the top line indicating the highest sounding string (high E). By placing a number on the appropriate line, the string and fret of any note can be indicated. The number 0 represents an open string. An ‘X’ means to muffle, not let it ring.