Braille Primer

Brief Overview of Current Braille Codes

The representation of letters, common punctuation marks, and a few other symbols as raised dot patterns readable by blind people was developed by Louis Braille in the early part of the 19th century.  Braille is a series of braille "cells" having raised dots on a grid of 2 columns and 3 rows. Embossed braille has approximately four cells per horizontal inch and 2.5 lines of cells per vertical inch.  Dot to dot spacing within a braille cell is approximately 0.1 inch, and the dot height is about 0.02 inches. 

Standard English Braille has two formats: Grade 1 (non-contracted) or Grade 2 (contracted).  Grade 1 symbols are single cells, but Grade 2 ("Braille Shorthand") has many double cell contractions and a long list of shorthand words. Several symbols are context dependent in grade 1, and many are context-dependent in grade 2. 

Every character in the braille code is based on an arrangement of one to six raised dots. Each dot has a numbered position in the braille cell. These characters make up the letters of the alphabet, punctuation marks, numbers, and everything else you can do in print.
The Braille Cell
	The letter "A" is written with only 1 dot.
	The letter "D" has dots 1, 4, and 5.
	The letter "Y" has dots 1, 3, 4, 5, and 6.
	A "Period" is written with dots 2, 5, and 6. (Do you see how it is the same shape as the letter "D," only lower down in the cell?)
	When all six dots are used, the character is called a "full cell"
	The picture below shows you how the dots are arranged in the braille cell for each letter of the alphabet. See if you can find the letters in your name and tell the dot numbers for each one.
	a   b   c   d   e   f   g   h   i   j   k   l   m   n   o   p   q   r   s   t   u   v   w   x   y   z
	Braille does not have a separate alphabet of capital letters as there is in print. Capital letters are indicated by placing a dot 6 in front of the letter to be capitalized. Two capital signs mean the whole word is capitalized.
	One Letter Capitalized            Entire Word Capitalized
Braille Numbers
	Braille numbers are made using the first ten letters of the alphabet, "a" through "j", and a special number sign, dots 3, 4, 5, and 6.
	#   0   1   2   3   4   5   6   7   8   9
	Larger numbers only need one number sign. The comma in braille is dot 2.

References:
  http://www.afb.org/
  http://dots.physics.orst.edu/gs_index.html