A mordent is an ornament in which a note is played with a single rapid alternation at its start with the note above or below it. The repeated segment of the note should be of longer duration than those of the first segment and the adjacent note, and it should bear the accent. Mordents are notated with a short horizontal wavy line with two sharp peaks and valleys that is placed above the affected note. A lower mordent, in which the secondary note is below the main note, is differentiated from an upper mordent by the addition of a short vertical line through it. As with trills, mordents can be chromatically modified by placing a small flat, sharp or natural symbol above or below them. Mordents differ from trills in that the latter have a rapid alternation with the adjacent tone for the entire duration of the note rather than just a single alternation at the beginning.