Do not use the lower groupsign for "ea", "bb", "cc", "ff", or "gg" when the letters it represents are preceded or followed by a capitals indicator or a capitals terminator.

To prevent it from being misread as "enough", do not use the lower groupsign for "en" when the letters "en" are "standing alone". Refer to: Section 2.6, Terminology and General Rules, for the definition of "standing alone".

Use the lower groupsign for "en" or "in" wherever the letters it represents occur unless other rules limit its use.

Do not use the lower groupsign for "ea" when the letters "ea" bridge a prefix and the remainder of the word.

Braille is a tactile method of reading and writing for blind people developed by Louis Braille (1809-1852), a blind Frenchman. The braille system uses six raised dots in a systematic arrangement with two columns of three dots, known as a braille cell. By convention, the dots in the left column are numbered 1, 2 and 3 from top to bottom and the dots in the right column are numbered 4, 5 and 6 from top to bottom.

Use line mode when it is advantageous to draw "lines" using standard braille cells. Line mode enables regular text and diagrammatic lines to coexist without ambiguity, even within the same diagram. Refer to: Section 7, Punctuation, for the hyphen, dash, long dash and low line; Guidelines for Technical Material, Part 4, for the lines in spatial calculations and other technical diagrams; and Part 16.7, for the lines and bonds in structural formulae used in chemistry.

The six dots of the braille cell are configured in 64 possible combinations (including the space which has no dots present). The 63 braille characters with dots are grouped in a table of seven lines. This table is used to establish "braille order" for listing braille signs.

Line 1 is formed with characters in the upper part of the cell, using dots 1, 2, 4 and 5.

Line 2 adds dot 3 to each of the characters in Line 1.

Line 3 adds dots 3 and 6 to each of the characters in Line 1.

Line 4 adds dot 6 to each of the characters in Line 1.

Line 5 repeats the dot configurations of Line 1 in the lower part of the cell, using dots 2, 3, 5 and 6.

Line 6 is formed with characters using dots 3, 4, 5 and 6.

Line 7 is formed with characters in the right column of the cell, using dots 4, 5 and 6.

Do not use line mode when the attributes of the lines or their relationship with one another is important, such as in the study of geometry or the measurement of angles.

Do not use line mode when the diagram would be too complex to be read by touch.