Earlier sources (before 1620 or so) use a system of chord notation, not unlike the shorthand used in popular guitar styles today. The Spanish sources called these “cifras,” and the Italians called them “alfabeto.” The chart below shows the typical letters that were used. The top line of the tablature represents the 5th course, or A-string. Some composers used a system that included fret numbers for the movable chords, for example, “H” is a B-flat major chord, an H with a 2 above it would denote a B major chord, with a 3 would be a C major chord, using the same fingering in the fret indicated. The French tablatures, which appear later, do not typically use the Alfabeto system, instead the frets of each chord are indicated directly. Some of the earlier Spanish sources use numbers instead of letters.


The example below is the first Spagnoletta from Giovanni Paolo Foscarini’s first book, from around 1620. It is very typical of the Italian Alfabeto sources. The vertical hash marks on the horizontal lines represent the direction of the strum. Below the line indicates a downward (from ceiling to floor) strum, above is an upward strum. The numbers on the line indicate the frets of notes that are added on the first course to the chords that are indicated. Note the fret numbers as discussed above to the movable chord fingerings. While there is a time signature indicated, there are often no barlines in these sources. This example begins on beat two, which probably would have been understood by the player as a feature of the the dance.
By 1630, Italian sources were using tablature in combination with Alfabeto, in what is typically called “mixed style.” Below is an example of this, from Angiol Michele Bartolotti’s 1640 book. In Italian tablature, the top line indicates the 5th course (closest to the ceiling), and numbers are used to indicate frets. Bartolotti also used hash marks to indicate direction of strumming. Some composers did this, others did not. Ligature marks indicate slurs, and dots are used to indicate right hand fingers. One dot for the index, two for the middle. The ⁒ symbol indicates a trill, which, in this style, begins on the main note. Composite rhythmic notation is indicated above the tablature. This system is also used in Spanish sources.
French sources, such as the example below from Robert de Visée’s 1686 book used letters to indicate frets. “a” is the open string, “b” the first fret and so on. There was no “j” so as to prevent confusion with “i.” The vertical lines indicate that two notes are to be played simultaneously with the thumb and fingers, “a pincer,” as opposed to strums. The commas represent trills (starting on the auxiliary note in French style). Ligatures represent slurs, and dots are right hand fingers. The straight lines, such as in measure three, indicate that notes are to ring. Strumming is indicated in French tablatures with noteheads in between the top two lines. A stem up indicates an upward strum, down indicates a downward strum. As in the Italian, rhythm is indicated with notes above the tablature, or with the strumming indications. The application of “notes inégales” is an accepted part of French baroque style. See this article for more explanation.