International uniformity of braille alphabets

The goal of braille uniformity is to unify the braille alphabets of the world as much as possible, so that literacy in one braille alphabet readily transfers to another.^[1] Unification was first achieved by a convention of the International Congress on Work for the Blind in 1878, where it was decided to replace the mutually incompatible national conventions of the time with the French values of the basic Latin alphabet, both for languages that use Latin-based alphabets and, through their Latin equivalents, for languages that use other scripts. However, the unification did not address letters beyond these 26, leaving French and German Braille partially incompatible and as braille spread to new languages with new needs, national conventions again became disparate. A second round of unification was undertaken under the auspices of UNESCO in 1951, setting the foundation for international braille usage today.

Braille arranged his characters in decades (groups of ten), and assigned the 25 letters of the French alphabet to them in order. The characters beyond the first 25 are the principal source of variation today.

In the first decade, only the top four dots are used; the two supplementary characters have dots only on the right. These patterns are repeated for the second decade, with the addition of a diacritic at dot 3; for the third, at dots 3 and 6; for the fourth, at 6; and for the fifth decade, by duplicating the first decade within the lower four dots.

Braille is in its origin a numeric code. Louis Braille applied the characters in numerical order to the French alphabet in alphabetical order. As braille spread to other languages, the numeric order was retained and applied to the local script. Therefore, where the alphabetical order differed from that of French, the new braille alphabet would be incompatible with French Braille. For example, French was based on a 25-letter alphabet without a w. When braille was adopted for English in the United States, the letters were applied directly to the English alphabet, so that braille letter of French x became English w, French y became English x, French z English y, and French ç English z. In the United Kingdom, however, French Braille was adopted without such reordering. Therefore, any English book published in braille needed to be typeset separately for the United States and the United Kingdom. Similarly, the letters for Egyptian Arabic Braille were assigned their forms based on their nearest French equivalents, so that for example Arabic d had the same braille letters as French d. For Algerian Arabic Braille, however, the braille characters were assigned to the Arabic alphabet according to the Arabic alphabetical order, so that Algerian d was the same character as Egyptian h. Thus an Arabic book published in Algeria was utterly unintelligible to blind Egyptians and vice versa.

In addition, in other alphabets braille characters were assigned to print letters according to frequency, so that the simplest letters would be the most frequent, making the writing of braille significantly more efficient. However, the letter frequencies of German were very different from those of English, so that frequency-based German braille alphabets were utterly alien to readers of frequency-based American Braille, as well as to numerically based German, English, and French Braille.

The 1878 congress, convening representatives from France, Britain, Germany, and Egypt, decided that the original French assignments should be the norm for those countries:

[Due to] the tendencies in America and Germany to re-arrange the Braille alphabet [to fit their own alphabetical orders], the Congress decided ... that it should be adopted ... with the values of its symbols unaltered from those of the original French.^[2]

Gradually the various reordered and frequency-based alphabets fell out of use elsewhere as well.

This decision covered the basic letters of the French alphabet at the time; w had been appended with the extra letters, so the 26 letters of the Basic Latin alphabet are slightly out of numeric order:

For non-Latin scripts, correspondences are generally based, where possible, on their historical connections or phonetic/transcription values.^[3] For example, Greek γ gamma is written ⠛g, as it is romanized, not ⠉c, as it is ordered in the alphabet or as it is related historically to the Latin letter c. Occasional assignments are made on other grounds, such as the International Greek Braille ω omega, which is written ⠺w, as in beta code and internet chat alphabets, due to the graphic resemblance of Latin w and Greek ω.

En 1929, en París, la Fundación Americana para Ciegos de Ultramar patrocinó una conferencia sobre la armonización del braille entre las lenguas que utilizan el alfabeto latino, que habían divergido en las décadas anteriores.

Cuando se necesitan letras adicionales para un nuevo alfabeto braille, se utilizan varios métodos.

1. Pueden tomarse prestadas de un alfabeto existente; por ejemplo, las consonantes francesas y alemanas ⠜ ä , ⠪ ö , y ⠳ ü se usan ampliamente cuando un idioma necesitaba una segunda vocal a, o o u. Del mismo modo, los valores de las consonantes inglesas contraídas ("Grade 2") ⠡ ch , ⠩ sh , y ⠹ th se usan ampliamente para sonidos similares en otros idiomas.
2. Una letra que de otro modo no se usaría puede ser reasignada. Por ejemplo, el Braille tibetano , que se basa en el Braille alemán, reasigna ⠉ c , ⠟ q , ⠭ x y ⠽ y , que son redundantes en alemán.
3. En el caso de los signos diacríticos en el alfabeto impreso, se puede añadir un punto a la letra base en braille. El braille letón , por ejemplo, añade el punto 6 para indicar un signo diacrítico, a costa de abandonar varias asignaciones internacionales.
4. Se pueden inventar nuevas letras modificando una letra similar. La modificación se puede hacer moviendo la letra (así ⠢ y ⠔ para una segunda vocal e o i ), estirándola (de nuevo, ⠡ y ⠌ para vocales parecidas a e e i ), o rotándola o reflejándola. Esto último es bastante común, produciendo pares como ⠎ s – ⠱ sh y ⠝ n – ⠫ ny . Véase el Braille húngaro para un alfabeto que ha explotado un patrón de imágenes especulares, y el Braille tailandés para la serie ⠧บb , ⠯ปp , ⠏ผph ₁ , ⠹พph ₂ .

En 1950 tuvo lugar una conferencia regional de la UNESCO sobre la uniformidad del braille para el sur de Asia. ^{[ 12 ]} Esto dio lugar a una conferencia de alcance mundial al año siguiente. El congreso de 1951 encontró muchas asignaciones de braille contradictorias:

La mayoría de las lenguas asiáticas y africanas contienen más letras o sonidos de los que el alfabeto romano tenía equivalentes, [y] tuvieron que encontrar alguna forma de representarlos. La mayoría de los diseñadores del Braille hablaban inglés y algunos recurrieron a las contracciones del Braille inglés para encontrar signos que sirvieran de precedente para los valores de las letras locales... Pero, además, muchos alfabetos no europeos incluían letras para las que no existía ningún precedente en Braille. Se tuvieron que asignar signos arbitrarios, con la consecuencia de que, incluso en estos Brailles tradicionales, solo se logró una uniformidad limitada. ^{[ 13 ]}

El congreso reconoció el papel del braille contraído en inglés en el establecimiento de un estándar internacional parcial y recomendó que los alfabetos sigan las convenciones existentes en la medida de lo posible.

• Meeting of the Advisory Committee on Braille Problems, Unesco, 1949
• "World Braille Usage" (2nd ed.). UNESCO. 1990. Retrieved 2012-04-19.