Braille is a reading and writing system of tactile dots for blind people. Braille was developed by, and named after, Louis Braille. Braille is not a "Universal Language" as some people assume, although many languages do use the same alphabet. There are many standard systems of braille for different languages and different purposes, such as encoding math or music.
The basic unit of braille is the cell. Many cells have multiple meanings, depending on the language or notation being used and other aspects of the surrounding text.
Standard braille characters (or "cells"), are composed of up to six dots arranged in two columns of three dot positions each. The dot positions are customarily numbered as follows:
1
• • 4
2 • • 5
3 • • 6
There are 64 possible combinations of raised dots within this pattern (counting the space, where no dots are raised).
A braille code is a system of assignments of meaning to the various combinations, together with rules for usage. For example, in English Braille, the dots 1-5 combination (that is, dots 1 and 5 raised, the others un-raised, in the same cell) normally means the letter "e," but in some circumstances it can also mean the digit "5" and in others it can be a contraction standing for the word "every." The rules of usage are such that the meaning in any instance is clear.
Some braille systems employ eight dots in a cell, or some other number or pattern of dots, typically for special uses other than general literary material.
A contraction is an abbreviated way of writing something in braille. For example, in English contracted (grade 2) braille, the word "the" is written as a single cell (dots 2346), rather than as the three cells that normally represent the individual letters. That same single-cell contraction is used in most, but not all, cases where the letters "t-h-e" occur within a word, as in "chrysanthemum." It is not used, however, in certain instances such as in the compound word "sweetheart."
Contractions sometimes use ordinary letters or other symbols, relying upon context clues to keep the meaning clear. For example, in English contracted braille, the contraction for the letters "ea" is the same cell (dot 2) that normally represents a comma -- and for that reason, the "ea" contraction is never used when it comes at the end of a word (as in "Chelsea").
Many contractions consist of several cells in braille.
In some languages, contractions can represent not only groups of letters and whole words but even groups of words. (Multi-word contractions are often called "locutions.")
Braille standards for Canada, New Zealand and the United States of America are set by the Braille Authority of North America (BANA). In the United States, the National Library Service for the Blind and Physically Handicapped of the Library of Congress sets standards, based upon BANA's, for its producers.
In the United Kingdom, the UK Association for Accessible Formats (UKAAF) (formerly BAUK) sets the braille standards.
In other countries and locations, standards may be set by a similar national or international authority, or by schools or agencies for the blind or other established producers.
The document entitled "Translation Tables Usage Guide," under Help, gives information about the standards followed for the various kinds of translation that can be carried out using DBT.
Many books have been written about Louis Braille and about the system of reading and writing that he developed; both subjects are too large for in-depth treatment in this help system. A good starting point for further information about braille is the resource section of Duxbury's web site at:
http://www.duxburysystems.com/info.asp