Braille Patterns

Short description: Unicode character block

Braille Patterns
Range	U+2800..U+28FF (256 code points)
Plane	BMP
Scripts	Braille
Assigned	256 code points
Unused	0 reserved code points
Source standards	ISO 11548-1
Unicode version history
3.0	256 (+256)
Note:

The Unicode block Braille Patterns (U+2800..U+28FF) contains all 256 possible patterns of an 8-dot braille cell, thereby including the complete 6-dot cell range. In Unicode, a braille cell does not have a letter or meaning defined. For example, Unicode does not define U+2817 ⠗ to be "R".

Symbols, not letters

In Unicode braille characters are not defined as belonging to any other script, but are defined as the Braille script. That is, the patterns are available as symbols, without connection to an alphabetic letter or a number. This is because the same symbol can be used in multiple scripts, e.g. as a Latin character, a Vietnamese character, a Chinese character and a digit. For example: although U+2813 ⠓ BRAILLE PATTERN DOTS-125 represents the letter "H" in basic braille, its Unicode definition makes no reference to "H", and it is just as valid representing Korean ᄐ t-, or Japanese り ri.

For this reason – a dot-pattern is not a letter – Unicode declares that, strictly speaking, braille patterns are 'symbols', not 'letters'. The General Property is "So" (Symbol, other), not "Lo" (Letter, other). Beyond that declaration, however, braille is treated as a script in multiple places. E.g., the character property "Script" for the 256 braille code points is ISO 15924 "Brai", for braille. This way, searching users and programs are led to the right place.

Identifying, naming and ordering

Braille dot numbering

Hexadecimal value of braille dots

The coding is in accordance with ISO/TR 11548-1 Communication aids for blind persons. Unicode uses the standard dot-numbering 1 to 8. Historically only the 6-dot cell was used in braille. The lower two dots were added later, which explains the irregular numbering 1-2-3-7 in the left column and 4-5-6-8 in the right column. Where dots 7 and 8 are not raised, there is no distinction between 6-dot and 8-dot definitions.

The Unicode name of a specific pattern mentions the raised dots: U+2813 ⠓ BRAILLE PATTERN DOTS-125 has dots 1, 2 and 5 raised. By exception, the zero dot raised pattern is named U+2800 ⠀ BRAILLE PATTERN BLANK.

In the 8-dot cell each dot individually can be raised or not. That creates 2⁸=256 different patterns. By mapping each of the eight dots to a bit in a byte (in a little-endian order), and by defining "0"/"1" for not raised/raised per bit, every specific pattern generates an identifying binary number. So the pattern with dots 1-2-5 raised would yield (00010011)₂, equivalent to (13)₁₆ or (19)₁₀.

The mapping can also be computed by adding together the hexadecimal values, seen at right, of the dots raised. So the pattern with dots 1-2-5 raised would yield 1₁₆+2₁₆+10₁₆ = 13₁₆. Whether computed directly in hexadecimal, or indirectly via binary, the result is added to 2800₁₆, the offset for the Braille Patterns Unicode block.

There is no regular mapping to the braille ASCII numbering.

Colloquial names

The Unicode names of braille dot patterns are not the same as what many English speakers would use colloquially. In particular, Unicode names use the word dots in the plural even when only one dot is listed: thus Unicode says braille pattern dots-5 when most English-speaking users of braille would simply say "braille dot 5" or just "dot 5".

In addition, some English-speaking users of braille use the word "and" when listing only two dots. Thus braille pattern dots-45 would be spoken as "braille dots 4 and 5". The word "and" is not always used when listing many dots however.

Block

Braille was added to the Unicode Standard in September, 1999 with the release of version 3.0.

When using punching, the filled (black) dots are to be punched.

The Unicode block for braille is U+2800 ... U+28FF:

Font differences

When showing braille graphically in printed instruction manuals, it can be useful to indicate the dots that are not punched, especially if a single braille cell of only one or two punched dots is shown out of context: in this case it might otherwise be difficult to judge the vertical alignment of the dots and tell the difference between, say, dots 2 and 4 versus dots 3 and 5.

The current Unicode charts, and some fonts, use empty circles to indicate dots that are not punched. This does not always render very clearly: if the circle outlines are printed heavily then it can be difficult to tell at a glance whether the dot is filled in or not. The braille package for LaTeX (and several printed publications such as the printed manual for the new international braille music code) show unpunched dots as very small dots (much smaller than the filled-in dots) rather than circles, and this tends to print better.

Some braille fonts do not indicate unpunched dots at all. Additionally, some Linux braille fonts (e.g. GNU Unifont and the DejaVu fonts) use small squares instead of small circles to indicate dots.

Other uses

The Braille Pattern characters are commonly used in terminal applications as a way to draw multiple pixels per character.

History

The following Unicode-related documents record the purpose and process of defining specific characters in the Braille Patterns block:

Version	Final code points	Count	UTC ID	L2 ID	WG2 ID	Document
3.0	U+2800..28FF	256		X3L2/90-064		Extracts from "A Proposal for Funding the Programs of Braille Research and Literacy", 1990-01-01
				X3L2/91-085		TC 173 Proposals for new work items for Braille Coding, 1991-03-20
				X3L2/92-039		Bishop, Avery (1991-10-29), The long awaited draft reply on Braille symbol encoding
					N1093	Shibano, Kohji (1994-12-26), Braille Letters
					N1203	Umamaheswaran, V. S.; Ksar, Mike (1995-05-03), Unconfirmed minutes of SC2/WG2 Meeting 27, Geneva
				X3L2/95-114	N1279	Braille letters (addition request), 1995-10-27
					N1303 (html, doc)	Umamaheswaran, V. S.; Ksar, Mike (1996-01-26), Minutes of Meeting 29, Tokyo
				X3L2/95-125		Duran, Peter (1990-05-24), A Proposal for Funding the Programs of Braille Research and Literacy
			UTC/1996-002			Aliprand, Joan; Hart, Edwin; Greenfield, Steve (1996-03-05), UTC #67 Minutes
			UTC/1996-007			Hart, Edwin (1996-03-07), Contribution on Encoding Braille in ISO/IEC 10646
					N1342	Sato, Takayuki K. (1996-03-19), Braille letters (confirmation of request)
					N1339	Ksar, Mike (1996-03-28), Liaison Letter on Braille to ISO/TC137 Secretariat
					N1345	Hart, Edwin (1996-04-01), Initial comments on encoding Braille into ISO/IEC 10646
					N1353	Umamaheswaran, V. S.; Ksar, Mike (1996-06-25), Draft minutes of WG2 Copenhagen Meeting # 30
			UTC/1996-027.2			Greenfield, Steve (1996-07-01), UTC #69 Minutes (PART 2)
					N1409R	Braille Symbols, 1996-08-12
					N1453	Ksar, Mike; Umamaheswaran, V. S. (1996-12-06), WG 2 Minutes - Quebec Meeting 31
					N1588	DIS 11 548-1 - Communication aids for blind persons Part 1: Braille identifiers and shift marks - General guidelines, 1997-06-23
					N1588.1	DIS 11 548-2 - Communication aids for blind persons Part 2: Latin alphabet based character sets
				L2/97-157	N1612	Report of ad-hoc group on Braille encoding, 1997-07-01
				L2/97-288	N1603	Umamaheswaran, V. S. (1997-10-24), Unconfirmed Meeting Minutes, WG 2 Meeting # 33, Heraklion, Crete, Greece, 20 June - 4 July 1997
				L2/98-136	N1770	Paterson, Bruce (1998-04-06), Revised Text of 10646-1/FPDAM 16: Amendment 16: Braille Patterns
				L2/98-286	N1703	Umamaheswaran, V. S.; Ksar, Mike (1998-07-02), Unconfirmed Meeting Minutes, WG 2 Meeting #34, Redmond, WA, USA; 1998-03-16--20