Fortunately for us, Robert ap Huw provided us with a key to these symbols, found on p. 35 of the manuscript. Starting on the left of the page, we are given three important pieces of information for each movement: its name (which can tell us quite a lot about the detail of the movement), the way it looks in the music text, and another version of each movement using a sort of staff notation with triangular noteheads. One should not be misled by the fact that Robert has sometimes given us the version in staff notation more than once for each movement. The remaining material in the diagram consists mostly of poorly informed additions by later owners of the manuscript, and may be disregarded.

The meanings of the symbols used in this diagrammatic explanation can be briefly given as follows:

The single and double oblique strokes above the note-names tell us the order in which the notes are to be played, and which of them are to be damped immediately (this is an important aspect of the fingering technique). The direction of the oblique strokes (upward or downward from left to right) tells us whether the first two notes to be played move downward or upward. The number of oblique strokes in each movement tells us how many of the notes in the movement are to be damped.

More precise information about this is given in the triangular notes. The black note-heads are notes which are to be damped. The notes with clear (white) heads are to be left sounding. The triangular notes are generally staggered in such a way as to show us the order in which the strings are to be played. It has also been established that the four different possible positions of the triangular notes are used to tell us which fingers strike the notes:

stem up, facing right — thumb

stem up, facing left — index finger

stem down, facing left — middle finger

stem down, facing right — ring finger

The names of two of these movements (taked y fawd and plethiad y bys bach) have led to the identification of the fingers which damp the strings immediately after they have been struck. This operates according to a system called "covering fingers", since a string is generally damped by a different finger from the one which struck it.

An example may make this all a little clearer. The movement "plethiad y bys bach" consists of three notes, with two oblique strokes ascending to the right above them. Thus, the first two notes move upwards (as, inevitably, does the third), and two notes are damped. The triangular notes tell us that the strings are played by the middle finger, the index finger and the thumb respectively. The first two of the notes are damped; the first by the ring finger, and the second by the little finger (which gives the movement its name: "plethiad of the little finger"). This movement involves all five fingers, and can be executed with economy of effort and at speed. This is typical of the movements as a whole.

We can classify all the movements which are symbolised by oblique strokes as "plethiadau" ("plaitings" or "weavings"), which is a good pictorial description of what the fingers are doing. The other major classification comes under the heading of "crychiadau" (literally "wrinklings" or "crumplings"). These movements use a variety of different symbols, some of which suggest at first the idea of a tremolo.

Painstaking examination of the diagram in conjunction with the music text has led to the conclusion that the crychiad movements are, according to context, either single strokes with the back of the nail, or two or more strokes backward and forward with the nail. It should be understood, then, that this fingering technique depends on the fingernails being grown and shaped so that the nail comes to the top of the finger-pad, and that they are used to pluck and strike the strings. The strings are damped with the tip of the finger-pad.