Braille pattern dots 4 and 7

The dot positions are fixed; their reading requires a Braille code. Braille is a system of raised dots read by touch. Each group of dots is called a cell. In an eight-dot cell, the left column is numbered 1, 2, 3, 7 from top to bottom; the right is 4, 5, 6, 8. In ⡈, only positions 4 and 7 are raised.

The name “47” lists two positions; it does not mean the number forty-seven. To read this cell as text, you need the language and the Braille convention being used. Unicode preserves the dot pattern without assigning it one letter. Ordinary text can instead remain in its own script and be converted to Braille by software.

Eight-dot Braille extends a system made for fingertips

Louis Braille developed his six-dot system at a Paris school where blind pupils read embossed letters. Charles Barbier presented a 12-dot method there in 1821; Braille developed a smaller cell by 1824 and published his method for words and music in 1829. A slate and stylus let people write by pressing dots into paper.

Eight-dot Braille adds a fourth row beneath the six-dot cell. This gives 256 possible patterns, including the blank cell, instead of 64. The extra positions are useful for representing computer text on refreshable Braille displays—devices whose pins rise to form tactile characters.