The mordent is made up by the swift alternation of three notes: royal, upper (or lower) auxiliary and royal. Its graphic sign is set above the note and can be of two types:
Upper mordent
, lower mordent 
The mordent subtracts some value to the note it is set on and the accent falls onto the first of the three notes.
If the auxiliary note must be altered, the alteration is set above (or below) the ornament.
The mordent can be even double, that is, composed of five sounds.
Example:
Examples of mordent on short-value notes:
