BabelStone

How many Unicode characters are there ?

2005-11-24

[Mirrored from http://babelstone.blogspot.com/2005/11/how-many-unicode-characters-are-there.html]

Otto Stolz asked on the Unicode List how many Unicode characters there were, classified as control characters, format characters, graphic characters, private use chacters, noncharacters, surrogate code points, etc. Now I love Unicode facts, figures and trivia, so I can't resist trying to answer this question.

The "Unicode Version History" utility of BabelMap provides precisely the information requested by Otto for all versions of Unicode from 1.0.0 up to the current version (4.1 when I first wrote this post, but now updated to 6.1). This information is tabulated below :

[Unicode Slide Show : 110,116 characters, one at a time]

BabelMap : Unicode Version History
Version	1.0.0	1.0.1	1.1	2.0	2.1	3.0	3.1	3.2	4.0	4.1	5.0	5.1	5.2	6.0	6.1
Date	October 1991	June 1992	June 1993	July 1996	May 1998	September 1999	March 2001	March 2002	April 2003	March 2005	July 2006	April 2008	October 2009	October 2010	January 2012
Scripts	24	25	24	25	25	38	41	45	52	59	64	75	90	93	100
Blocks	57	59	63	67	67	86	95	107	122	142	151	168	194	206	217
Total Code Points	65,536	65,536	65,536	1,114,112	1,114,112	1,114,112	1,114,112	1,114,112	1,114,112	1,114,112	1,114,112	1,114,112	1,114,112	1,114,112	1,114,112
Assigned Code Points	12,795	34,505	40,635	178,500	178,502	188,809	233,787	234,803	236,029	237,302	238,671	240,295	246,943	249,031	249,763
Unassigned Code Points	52,741	31,031	24,901	935,612	935,610	925,303	880,325	879,309	878,083	876,810	875,441	873,817	867,169	865,081	864,349
Encoded Characters	7,161	28,359	34,233	38,950	38,952	49,259	94,205	95,221	96,447	97,720	99,089	100,713	107,361	109,449	110,181
Private Use Characters	5,632	6,144	6,400	137,468	137,468	137,468	137,468	137,468	137,468	137,468	137,468	137,468	137,468	137,468	137,468
Non characters	2	2	2	34	34	34	66	66	66	66	66	66	66	66	66
Surrogate Code Points	0	0	0	2,048	2,048	2,048	2,048	2,048	2,048	2,048	2,048	2,048	2,048	2,048	2,048
Graphic Characters	7,085	28,283	34,151	38,867	38,869	49,168	94,009	95,023	96,243	97,515	98,884	100,507	107,154	109,242	109,975
Format Characters	2	2	2	18	18	26	131	133	139	140	140	141	142	142	141
Control Characters	74	74	80	65	65	65	65	65	65	65	65	65	65	65	65

For historic versions of Unicode the statistics are based on the General Category of the characters at the time of encoding, and do not take into account any subsequent changes in General Category. Thus the fact that 4.0 has 139 format characters and 4.1 has 140 format characters is not due to a new format character having been added in 4.1, but rather due to the General Category of U+200B ZERO WIDTH SPACE having been changed from Zs to Cf in Unicode 4.0.1. Note that the statistics for 1.0.0 and 1.0.1 are based upon Ken Whistler's reconstructed Unicode Character Data.

To help understand what we're talking about, here are some definitions of some of the terms used in the table (see Section 2.4 of the Unicode Standard for further information).

Control characters are those characters with a General Category of 'Cc'. These are invisible characters that perform a certain function that is defined by a protocol or standard other than Unicode (they are inherited from pre-existing 8-bit standards). They include familiar characters such as Tab, Carriage Return and Line Feed that are essential to writing Unicode (U+2028 LINE SEPARATOR and U+2029 PARAGRAPH SEPARATOR never took off as Unicode replacements for Carriage Return and/or Line Feed), as well as many characters that you should never see in plain text (the full range of control characters is 0000..001F and 007F..009F).
Format characters are those characters with a General Category of 'Cf', 'Zl' or 'Zp'. These are invisible characters defined by Unicode for a particular function. These include things like U+200D ZERO WIDTH JOINER, U+202D LEFT-TO-RIGHT OVERRIDE, interlinear annotation characters (FFF9..FFFB) and the infamous set of Tag characters (E0001 and E0020..E007F). They work behind the scenes to do useful things like bidirectional control and character shaping.
Graphic characters are those characters with a General Category other than Cc, Cn, Co, Cs, Cf, Zl and Zp, that is to say ordinary visible characters.
Noncharacters are code points that are permanently reserved, and are guaranteed never to be assigned as characters. They are the thirty-four code points ending in xxFE and xxFF, as well as the thirty-two code points in the range FDD0..FDEF.
Encoded characters = Graphic characters + Format characters + Control characters.
Assigned code points = Encoded characters + Private Use characters + Noncharacters + Surrogate code points.
Total code points = Assigned code points + Unassigned code points.

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