VISCII

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VISCII is a character encoding for using the Vietnamese language with computers.

Unicode and the Windows-1258 code page are now used for virtually all Vietnamese computer data, but legacy VSCII and VISCII files may need conversion.

VISCII is a modified ASCII. It keeps the 95 printable characters of ASCII unmodified, but it replaces 6 of the 33 control characters with printable characters. It adds 128 precomposed characters.

History[edit]

A traditional extended ASCII character set consists of the ASCII set plus up to 128 characters. Vietnamese requires 134 additional letter-diacritic combinations, which is six too many. There are essentially three different ways to handle this problem:

  1. Use variable-width encoding
  2. Use combining diacritical marks (as do VSCII and Windows-1258)
  3. Replace six of the basic ASCII control characters

VISCII went for the last option, replacing six of the least problematic (e.g., least likely to be recognised by an application and acted on specially) (C0 control codes STX, ENQ, ACK, DC4, EM, and RS) with six of the least-used uppercase letter-diacritic combinations. While this option may cause programs that use those control codes to malfunction when handling VISCII text, it creates fewer complications than the other two options. However, using up all the extended code points for accented letters left no room to add useful symbols, superscripted numbers, curved quotes, proper dashes, etc., like most other extended ASCII character sets.

VISCII was designed by the Vietnamese Standardization Working Group (Viet-Std Group) based in Silicon Valley, California in 1992 while they were working with the Unicode consortium to include precomposed Vietnamese characters in the Unicode standard. It is mentioned in RFC 1456, though incorrectly dubbed "VIetnamese Standard Code for Information Interchange" (the same name taken by VSCII).

Support[edit]

VISCII is partially supported by the TriChlor Software Group in California, which released a lot of software packages, libraries, and fonts for MS-DOS and Windows, Unix, and Macintosh. VISCII-compliant software is still available at many FTP sites.

Character set[edit]

  Letter   Number   Punctuation   Symbol   Other   undefined

VISCII
_0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _A _B _C _D _E _F
0_ NUL
0000
0
SOH
0001
1

1EB2
2
ETX
0003
3
EOT
0004
4

1EB4
5

1EAA
6
BEL
0007
7
BS
0008
8
HT
0009
9
LF
000A
10
VT
000B
11
FF
000C
12
CR
000D
13
SO
000E
14
SI
000F
15
1_ DLE
0010
16
DC1
0011
17
DC2
0012
18
DC3
0013
19

1EF6
20
NAK
0015
21
SYN
0016
22
ETB
0017
23
CAN
0018
24

1EF8
25
SUB
001A
26
ESC
001B
27
FS
001C
28
GS
001D
29

1EF4
30
US
001F
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_
1EA0
128

1EAE
129

1EB0
130

1EB6
131

1EA4
132

1EA6
133

1EA8
134

1EAC
135

1EBC
136

1EB8
137

1EBE
138

1EC0
139

1EC2
140

1EC4
141

1EC6
142

1ED0
143
9_
1ED2
144

1ED4
145

1ED6
146

1ED8
147

1EE2
148

1EDA
149

1EDC
150

1EDE
151

1ECA
152

1ECE
153

1ECC
154

1EC8
155

1EE6
156
Ũ
0168
157

1EE4
158

1EF2
159
A_ Õ
00D5
160

1EAF
161

1EB1
162

1EB7
163

1EA5
164

1EA7
165

1EA9
166

1EAD
167

1EBD
168

1EB9
169
ế
1EBF
170

1EC1
171

1EC3
172

1EC5
173

1EC7
174

1ED1
175
B_
1ED3
176

1ED5
177

1ED7
178

1EE0
179
Ơ
01A0
180

1ED9
181

1EDD
182

1EDF
183

1ECB
184

1EF0
185

1EE8
186

1EEA
187

1EEC
188
ơ
01A1
189

1EDB
190
Ư
01AF
191
C_ À
00C0
192
Á
00C1
193
Â
00C2
194
Ã
00C3
195

1EA2
196
Ă
0102
197

1EB3
198

1EB5
199
È
00C8
200
É
00C9
201
Ê
00CA
202

1EBA
203
Ì
00CC
204
Í
00CD
205
Ĩ
0128
206

1EF3
207
D_ Đ
0110
208

1EE9
209
Ò
00D2
210
Ó
00D3
211
Ô
00D4
212

1EA1
213

1EF7
214

1EEB
215

1EED
216
Ù
00D9
217
Ú
00DA
218

1EF9
219

1EF5
220
Ý
00DD
221

1EE1
222
ư
01B0
223
E_ à
00E0
224
á
00E1
225
â
00E2
226
ã
00E3
227

1EA3
228
ă
0103
229

1EEF
230

1EAB
231
è
00E8
232
é
00E9
233
ê
00EA
234

1EBB
235
ì
00EC
236
í
00ED
237
ĩ
0129
238

1EC9
239
F_ đ
0111
240

1EF1
241
ò
00F2
242
ó
00F3
243
ô
00F4
244
õ
00F5
245

1ECF
246

1ECD
247

1EE5
248
ù
00F9
249
ú
00FA
250
ũ
0169
251

1EE7
252
ý
00FD
253

1EE3
254

1EEE
255
_0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _A _B _C _D _E _F

See also[edit]

References[edit]

Further reading[edit]

  • Flohr, Guido (2016) [2006]. "Locale::RecodeData::VISCII - Conversion routines for VISCII". CPAN libintl-perl. Archived from the original on 2017-01-14. Retrieved 2017-01-14.
  • https://www.math.nmsu.edu/~mleisher/Software/csets/VISCII.TXT

External links[edit]