A glissando is a rapid ascending or descending of the scale on an instrument or instruments, a 'gliding' through consecutive pitches. When it is performed on a piano or harp not every semitone is sounded, because the finger is drawn across only the white keys of the former and only the scale available on the latter. If, however, it is performed on a bowed stringed instrument, such as a violin, each semitone would be sounded as the finger is slid up or down the length of the string. Glissandos can also be performed on wind instruments, although each note must be fingered separately. The notable exception is the trombone, because it has no valves or keys, and thus glissando is particularly easy on it. Glissandos are most commonly notated with a line, sometimes wavy, between the starting and end notes and often accompanied by the abbreviation gliss., although occasionally they are notated using semiquavers accompanied by the word 'glissando.'