Complete description of gabc

Notation fundamentals

Pitch

We have chosen to represent pitch using only one character. A character corresponds to a written pitch: whatever the key, a position on the stave will still be represented by the same character. With this system, anyone will be able to type scores, even people who do not know about music theory.

There are 13 possible pitches in Gregorian chant, which are represented by letters from a to m that is, 13 characters. For the rare pieces with other notes, the clef changes.

The problem of such a choice is that it corresponds to English notation only when the key of C is on the fourth line.

It seems that the problem is less awkward than in modern music, because Gregorian chant is hardly never transposed.

Of course, we can think that software like Denemo could let their users choose between typing notes and typing heights on the score.

One-note neumes

In the notation adopted, a lower-case letter, from a to m, represents a punctum quadratum, and an upper-case letter a punctum inclinatum, which are less frequently used.

For the virga, we have to take two letters: to obtain a virga you type a v (upper or lower-case) after the letter (lower ou upper-case too).

For the oriscus, it is the same but with an o.

Complex neumes

To compose a neume with more than one note, you simply type the letters corresponding to the notes, paying no attention to the links between them. The latter will be calculated automatically. In this example and the following, the letters that follow the legend are the one correspondig to the image in gabc notation.

When a quilisma is inside a neume, you type a w after the corresponding pitch.

When we need to do a stropha we add an s after the corresponding note. Theoretically, stropha never exist alone and they are grouped in twos or threes (distropha or tristropha)

Of course there are cases in which a sequence of notes can be written in different ways. These cases are described in the Determination of the neume according to the sequence of notes section.

Separation bars

Separation bars indicate a pause in the chant, so punctuation signs have been chosen to represent them.

The quarter of a bar on the top line is noted using , , the half-bar on the middle two lines is noted using ; , the complete bar is noted using : , and finally the double bar corresponds to :: .

The virgula, on the top line is noted using ` .

When the bars are between two syllables, you must type them in a separate syllable, for example jus(g) (::) Di(g).

When there is a :, it is in the text, so you must type it as normal text, not, for example, as text under a bar : do jus :(g) (:) instead of jus(g) :(:).

The clef

In most softwares, such as Lilypond, it does not seem to be of any use to define a fast way of typing the clef, because it is defined somewhere else. This is not a problem, as in most scores there is only one clef.

In the case where it could be used, in clef changes for example, we have defined a fast way to note this, using two characters:

• a letter corresponding to the symbol: c or f
• a number between 1 and 4 corresponding to the line on which the clef is written. We consider here that the lines are numbered from the bottom to the top.

It is very simple to write text: the letters corresponding to the texte are typed in brackets after the syllable to which they correspond. Brackets are used instead of braces because they are easier to type on a French keyboard.

To set the limits of the words, you simply put a space between them. We can now give an example of the final notation:

The text here is Populus Sion and each syllable is followed by the corresponding neume between brackets.

When the separation bars are not above text, we proceed the same way, but without text:

Text centering

In gregorian chant, centering the text can be done automatically (cf. the page about graphy). However, in many software programs, it is necessary to specify the part of the text on which the neume will be centered. Usually you do not have to indicate this, but if it is necessary, put the part of the text to be centered between braces.

Special characters

We must consider the notation of all texts: sometimes the texts of Gregorian chants contain non-unicode characters. Special characters used in Gregorian notation are the y accentuated, æ accentuated, œ accentuated, the crossed R (for répons), the crossed V (for verset) and the crossed A (for antienne). œaccentuated and the crossed A are not to be found in unicode tables.

In the case where it is not possible to do so using the keyboard, special characters will be inserted between sp markups, for example <sp>R/</sp> for the crossed R, <sp>'ae</sp> for æ accentuated.

Text style

Even if it does not seem necessary to envisage style for the text, we made some markups to apply styles to the text: they are <i> for italic, <b> for bold and <sc> for small capitals.

For example, <i>Ps.</i>(::)

Advanced notation

Liquescentiae and initio debilis figures

The notation of an initio debilis is simple: you simply add a - at the beginning of the neume.

For liquescentiae, three types exist, which are indicated by characters at the end of the neumes:

• diminutive liquescentiae, indicated by
• increasing liquescentiae
  • ascendae indicated by <
  • descendae indicated by >

Liquescentiae are indicated after other characters that determine the note.

Rhythm signs

The puctum mora (points after the note) are denoted by adding a . after the note. When there are two points after a note, the character is simply doubled: .. .

The vertical episemus does not pose a problem; it is denoted by a ' after the note.

Of course, several punctum mora and episemus can be present in one neume, but only one per note.

For the horizontal episemus, the problem is that it can apply to a whole group of notes.

Two solutions are considered:

• first we can type a _ after every note that is under an episemus.
• the second solution is to type at the end of a group of notes with episemus as many _s as the number of notes under the episemus. For example, if the group abc has an episemus, we would denote abc___ instead of a_b_c_.

The notation of rhythmic signs is after that of liquecenciae and other signs that determine the shape of the note. For example, a virga followed by a punctum mora is denoted hv. and not h.v, and a torculus deminutus followed by a punctum mora is denoted ghg~. .

In an antiphonary dating from 1931, there are sometimes two levels of horizontal episemus: a short episemus beneath a longer one. But this is very rare, and as many people think these accumulations are cumbersome, they are not envisaged in this notation.

Flats and naturals

Two letters have been chosen to represent the flat and the natural: x y. As these signs take the space of a note, we denote them like a note, for example, xi for a flat on the note represented by i.

Spaces

Spaces are very important in Gregorian chant. When monks transposed scores from ancient notation to square notation, the equivalence was not exact, and some ancient notations have been transposed by a larger space between two notes of a same neume. Although this phenomenon is quite rare, it exists, and it is necessary to take it into consideration in order to preserve every detail of a work.

Five spaces are used in Gregorian chant:

• neumatic cut: inside a neume, elements are separated by this space, which is the smallest
• large neumatic cut: this is the space described in the paragraph above; it is used in the same way as the neumatic cut, but the space is larger
• glyph space: this is the space described in the paragraph above; it is used in the same way as the neumatic cut, but the space is larger
• syllabic space: the space between two neumes corresponding to two syllabics of the same word
• word space: the space between two words. This space is more difficult: it is the space between both the letters and the notes of two different words. This space is also the one between words and separation bars.

The neumatic cut is denoted by /, and the larger neumatic space, more rare, by //. . A glyph space is indicated by a normal space. Syllabic and word spaces are automatically calculated by the software, according to the text, and this poses no difficulty. The glyph space could also be automatically included when there is a climacus with an interval of 2 notes or more.

Determination of the neume according to the sequence of notes

First we should say that it is no use putting virga in a neume, as linking bars between notes will be automatically added when necessary. Except for virga (which can be a glyph inside another neume), bivirga or trivirga neumes, you must not type a v when you type the sequence of a neume.

One and only one written form corresponds to any sequence of notes and spaces. The only exception is the sequence of three ascending notes. To determine the written form to use in this case, we must introduce a character to prevent the linking between two notes. This character is ! , which allows complete equivalence between our notation and the written form. People typing blindly (without visualizing the score) with this notation must be extremely cautious with this sign and must not forget its meaning.

Optional characters and repetitions

For neumes that repeat the same note several times, it is possible to achieve faster notation, in the following way. For example, for the bivirga two v are added after the note, and for the tristropha three s. Of course, the result will be the same if each detail is written: hs/hs/hs = hsss.

Advanced details

The podatus

The podatus poses a difficulty for square notation in general, because there are seven ways of denoting it in ancient notation, and much fewer in square notation. In the Solesmes hymnary of 1983, two new notations were introduced: the pesquassus and the podatus initio debilis. The first is written using an o after the first note, as it is an oriscus, and the second is written logically with a - before the first note.

A new written form of the podatus is also proposed here. It could be used to distinguish pes quadratus of the old notation that is currently transposed in the same way that the light pes or the pes with episemus are. In this new written form of the podatus, the second note is to the right of the bar that links the two notes, not to the left. These pes quadratus are denoted with a q between the two notes.

The polyphony

The first polyphonic pieces were written in square notation, even if the latter is slightly different from more recent notation. The goal of this notation is to represent Gregorian chant, when sung by only one voice, however it seemed important to consider the case of people who would want to write polyphonic scores in square notation. Polyphonies are different only at the level of the neume; indeed, the text is the same for all the voices (but usually only two). We propose separating the voices using the character & .

Empty notes and accents

In our notation, we do not consider the empty notes and the accents used at the beginning of some books to explain how to sing. The philosophy of our notation is to propose a simple way to write scores, not to write books, so we do not consider these signs.

Ends of line

Ends of line and custos can be automatically generated by the software. However it can be useful for some software to denote it, which is why we decided on a way of writing it: it would simply be z.

Unforeseen points and comments

If some aspects have been overlooked or if a new written form should appear, many ASCII characters have not yet been used in our notation and remain available, for example, the letters n p r t et u, both upper- and lower-case.

If comments or aspects specific to the software need to be inserted, square brackets would be appropriate.

Conclusion and extensions

We hope that we have described here the main aspects that need to be considered for the fast notation of Gregorian chant, and we hope that this notation will be implemented. All questions and remarks are welcome on the gregorio developers mailing list.

This notation does not consider the ancient neume notation. Although the latter is important, a completely different technique is needed for it, which we may consider at a later stage.

Complete example