ISO/IEC 6937

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ISO/IEC 6937:2001, Information technology — Coded graphic character set for text communication — Latin alphabet, is a multibyte extension of ASCII, or rather of ISO/IEC 646-IRV. It was developed in common with ITU-T (then CCITT) for telematic services under the name of T.51, and first became an ISO standard in 1983. Certain byte codes are used as lead bytes for letters with diacritics (accents). The value of the lead byte often indicates which diacritic that the letter has, and the follow byte then has the ASCII-value for the letter that the diacritic is on. Only certain combinations of lead byte and follow byte are allowed, and there are some exceptions to the lead byte interpretation for some follow bytes. Note, however, that no combining characters at all are encoded in ISO/IEC 6937. But one can represent some free-standing diacritics, often by letting the follow byte have the code for ASCII space.

ISO/IEC 6937's architects were Hugh McGregor Ross, Peter Fenwick, Bernard Marti and Loek Zeckendorf.

ISO6937/2 defines 327 characters found in modern European languages using the Latin alphabet. Non-Latin European characters, such as Cyrillic and Greek are not included in the standard. Also, some diacritics used with the Latin alphabet like the Romanian comma are not included, using cedilla instead as no distinction between cedilla and comma below was made at the time.

IANA has registered the charset names ISO_6937-2-25 and ISO_6937-2-add for two (older) versions of this standard (plus control codes). But in practice this character encoding is unused on the Internet.

The ISO/IEC 2022 escape sequence to specify the right-hand side of the ISO/IEC 6937 character set is ESC - R (hex 1B 2D 52).[1]

Single byte characters[edit]

The primary set of ISO6937/2 is based on ISO646 (characters 0x00..0x7f) with the exception of character 0x24 ($) which is denoted as a "general currency sign" (¤):

        !"#¤%&`()*+'-./0123456789:;<=>?@
        ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`
        abcdefghijklmnopqrstuvwxyz{|}

The supplementary set (characters 0x80..0xff) contains a selection of spacing and non-spacing graphic characters, additional symbols and some locations reserved for future standardisation.

Two byte characters[edit]

The characters which are not represented in the primary set are coded on two bytes. The first byte the "non spacing diacritical mark" is followed by a letter from the base set e.g.:

small e with acute accent (é) = [Acute]+e

In total 13 diacritical marks can be followed by the selected characters from the primary set:

Accent Code Second character Result
Grave 0xC1 AEIOUaeiou ÀÈÌÒÙàèìòù
Acute 0xC2 ACEILNORSUYZacegilnorsuyz ÁĆÉÍĹŃÓŔŚÚÝŹáćéģíĺńóŕśúýź
Circumflex 0xC3 ACEGHIJOSUWYaceghijosuwy ÂĈÊĜĤÎĴÔŜÛŴŶâĉêĝĥîĵôŝûŵŷ
Tilde 0xC4 AINOUainou ÃĨÑÕŨãĩñõũ
Macron 0xC5 AEIOUaeiou ĀĒĪŌŪāēīōū
Breve 0xC6 AGUagu ĂĞŬăğŭ
Dot 0xC7 CEGIZcegz ĊĖĠİŻċėġż
Umlaut or diæresis 0xC8 AEIOUYaeiouy ÄËÏÖÜŸäëïöüÿ
Ring 0xCA AUau ÅŮåů
Cedilla 0xCB CGKLNRSTcklnrst ÇĢĶĻŅŖŞŢçķļņŗşţ
DoubleAcute 0xCD OUou ŐŰőű
Ogonek 0xCE AEIUaeiu ĄĘĮŲąęįų
Caron 0xCF CDELNRSTZcdelnrstz ČĎĚĽŇŘŠŤŽčďěľňřšťž

Codepage layout[edit]

Note that the reference to combining characters in the U+0300—U+036F range for the codes in the range 0xC1—0xCF below are only indicative of which “accent” is usually intended by that lead byte. ISO/IEC 6937 does not encode any combining characters whatsoever. Instead there is an explicit list of precomposed characters that are encoded.

A little anomaly is that Latin Small Letter G with Cedilla is coded as if it were with an acute accent, that is with a 0xC2 lead byte, since due to its descender interfering the glyph usually looks that way (Ģ ģ). In Unicode, the ohm sign 0xE0 is unified with the Greek Capital Letter Omega which ISO 6937 does not include. Unicode also distinguishes 0xE2 into uppercase Eth and D with stroke, which usually look different for the lowercase letters (0xF2 and 0xF3).

Legend:

  Alphabetic
  Control character
  Numeric digit
  Punctuation
  Extended punctuation
  Graphic character
  International
  Undefined
ISO/IEC 6937 (Latin)
_0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _A _B _C _D _E _F
 
0_
 


0


1


2


3


4


5


6


7


8


9


10


11


12


13


14


15
 
1_
 


16


17


18


19


21


21


22


23


24


25


26


27


28


29


30


31
 
2_
 
SP
0020
32
!
0021
33
"
0022
34
#
0023
35
$
0024
36
%
0025
37
&
0026
38
'
0027
39
(
0028
40
)
0029
41
*
002A
42
+
002B
43
,
002C
44
-
002D
45
.
002E
46
/
002F
47
 
3_
 
0
0030
48
1
0031
49
2
0032
50
3
0033
51
4
0034
52
5
0035
53
6
0036
54
7
0037
55
8
0038
56
9
0039
57
:
003A
58
;
003B
59
<
003C
60
=
003D
61
>
003E
62
?
003F
63
 
4_
 
@
0040
64
A
0041
65
B
0042
66
C
0043
67
D
0044
68
E
0045
69
F
0046
70
G
0047
71
H
0048
72
I
0049
73
J
004A
74
K
004B
75
L
004C
76
M
004D
77
N
004E
78
O
004F
79
 
5_
 
P
0050
80
Q
0051
81
R
0052
82
S
0053
83
T
0054
84
U
0055
85
V
0056
86
W
0057
87
X
0058
88
Y
0059
89
Z
005A
90
[
005B
91
\
005C
92
]
005D
93
^
005E
94
_
005F
95
 
6_
 
`
0060
96
a
0061
97
b
0062
98
c
0063
99
d
0064
100
e
0065
101
f
0066
102
g
0067
103
h
0068
104
i
0069
105
j
006A
106
k
006B
107
l
006C
108
m
006D
109
n
006E
110
o
006F
111
 
7_
 
p
0070
112
q
0071
113
r
0072
114
s
0073
115
t
0074
116
u
0075
117
v
0076
118
w
0077
119
x
0078
120
y
0079
121
z
007A
122
{
007B
123
|
007C
124
}
007D
125
~
007E
126
DEL
007F
127
 
8_
 


128


129


130


131


132


133


134


135


136


137


138


139


140


141


142


143
 
9_
 


144


145


146


147


148


149


150


151


152


153


154


155


156


157


158


159
 
A_
 
NBSP
00A0
160
¡
00A1
161
¢
00A2
162
£
00A3
163


164
¥
00A5
165


166
§
00A7
167
¤
00A4
168

2018
169

201C
170
«
00AB
171

2190
172

2191
173

2192
174

2193
175
 
B_
 
°
00B0
176
±
00B1
177
²
00B2
178
³
00B3
179
×
00D7
180
µ
00B5
181

00B6
182
·
00B7
183
÷
00F7
184

2019
185

201D
186
»
00BB
187
¼
00BC
188
½
00BD
189
¾
00BE
190
¿
00BF
191
 
C_
 


192
̀
0300
193
́
0301
194
̂
0302
195
̃
0303
196
̄
0304
197
̆
0306
198
̇
0307
199
̈
0308
200


201
̊
030A
202
̧
0327
203


204
̋
030B
205
̨
0328
206
̌
030C
207
 
D_
 

2015
208
¹
00B9
209
®
00AE
210
©
00A9
211

2122
212

266A
213
¬
00AC
214
¦
00A6
215


216


217


218


219

215B
220

215C
221

215D
222

215E
223
 
E_
 
Ω
2126
224
Æ
00C6
225
Đ
0110
226
ª
00AA
227
Ħ
0126
228


229
IJ
0132
230
Ŀ
013F
231
Ł
0141
232
Ø
00D8
233
Œ
0152
234
º
00BA
235
Þ
00DE
236
Ŧ
0166
237
Ŋ
014A
238
ʼn
0149
239
 
F_
 
ĸ
0138
240
æ
00E6
241
đ
0111
242
ð
00F0
243
ħ
0127
244
ı
0131
245
ij
0133
246
ŀ
0140
247
ł
0142
248
ø
00F8
249
œ
0153
250
ß
00DF
251
þ
00FE
252
ŧ
0167
253
ŋ
014B
254
SHY
00AD
255
_0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _A _B _C _D _E _F

References[edit]

  1. ^ Supplementary Set of ISO/IEC 6937:1992 The high-ASCII half of the character set. (The left-hand side is U.S. ASCII.)