For the mordent the string should be plucked once only by the right hand while fretting with the left hand finger (see A), which should then be quickly raised and reapplied (see B and C). It is indicated in old books of guitar music as "v" or "+" (See E and F). Currently it is no longer indicated, but it is left to good taste and custom to decide where it is appropriate. It works very well on long notes like semibreves, minims (half-notes), and crotchets (quarter notes) in slow movements. When applied to the tonic (see G), it should be played with the leading note (leading tone) which is a semitone below the tonic (see D). This produces the effect known as "martellement" in wind and string instruments, and as "pincé" on the harpsichord and the organ. [Translator's note: In English the term "mordent" is used for both]
The trill or shake is played by plucking the same string several times in quick succession with one of the left hand fingers. The little finger should be given particular study, this being the most difficult. The trill is started on the higher note (see A). It is indicated by a (t) or a (+).