Files in this directory
=======================

All files with .tbl sufix are braille tables that may be used with
BRLTTY.  Note that BRLTTY has its own braille table format and it may
slightly differ from other braille table files.

There are a few tools provided in this directory to manipulate
those braille tables.  To build the tools, simply run 'make'.  The
following tools will be made:

tbl2txt 	outputs an ASCII list file from a braille table file (so
		the result can be modified with a regular text editor).
txt2tbl		outputs a braille table file from an ASCII list file
		(as produced with tbl2txt).
convtable	converts braille table files between different dot 
		mappings.
ibm437toiso	converts braille table files from the IBM code page 437
		to the ISO-8859-1 character set.
ibm850toiso	converts braille table files from the IBM code page 850
		to the ISO-8859-1 character set.


BRLTTY Braille Table Format
===========================

Each table consists of a binary file made up of 256 bytes.  The byte
offsets correspond to the value of any ASCII character to translate
into braille dots.  Each bytes gives the braille dot pattern for each
256 characters.  The bits are distributed as follows:

	bit 0	bit 1		-->	dot 1	dot 4
	bit 2	bit 3		-->	dot 2	dot 5
	bit 4	bit 5		-->	dot 3	dot 6
	bit 6	bit 7		-->	dot 7	dot 8

This dot mapping was chosen because it makes programming prettier for
underlining, cursor support or downshifting braille characters.

This means that any braille terminal that accepts a direct mapping 
bits 01234567 = dots 12345678 or any other dot mapping convention
must translate the dot pattern into its own mapping in its driver.

Also note that the byte offset which is the character value is 
assumed to be from the ISO-8859-1 character set by BRLTTY.

