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IS0
I N T ER N AT I O N AL O R G A N I ZAT I O N FO R STA N D AR D I Z AT I O N
IS0 RECOMMENDATION
R 646
6 AND 7 BIT CODED CHARACTER SETS
FOR INFORMATION PROCESSING INTERCHANGE
1st EDITION
December 1967
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized &herefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the oniy valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 646, 6 and 7 bit coded character sets for information
processing interchange, was drawn up by Technical Committee ISO/TC 97, Computers
and iigormation processing, the Secretariat of which is held by the United States of America
Standards Institute (USASI).
Work on this question by the Technical Committee began in 1962 and led, in 1966,
to the adoption of a Draft IS0 Recommendation.
In October 1966, this Draft IS0 Recommendation (No. 1052) was circulated to all
the IS0 Member Bodies for enquiry. It was approved, subject to a few modifications of
an editorial nature, by the following Member Bodies :
Argentina Germany Turkey
Australia Israel U.A.R.
Belgium Italy United Kingdom
Brazil
Netherlands U.S.A.
Canada Sweden U.S.S.R.
France Switzerland
Four Member Bodies opposed the approval of the Draft:
Austria
Japan
Poland
Spain
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in December 1967, to accept it as an IS0 RECOMMENDATION.
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IS0 / R 646 - 1967 (E)
I SO Recommendation R 646 Decem ber 1967
6 AND 7 BIT CODED CHARACTER SETS
FOR INFORMATION PROCESSING INTERCHANGE
1. GENERAL
1.1 Scope
1.1.1
This IS0 Recommendation describes two character sets for general usage, including
letters, figures, punctuation marks, other symbols and controls, with their coded repre-
sentation.
1.1.2
The requirements for graphics and controls in data handling and programming, in
accordance with computer and ancillary equipment characteristics, have been taken
into account in determining these character sets.
1.1.3 This IS0 Recommendation consists of two tables with notes, a key, explanatory notes
and the definitions of functional characteristics related to control characters.
1.1.4
These character sets are primarily intended for the interchange of information among
data processing systems and associated equipment. They may be regarded as basic
alphabets in an abstract sense.
1.1.5
These character sets are applicable to all Latin alphabets.
1.1.6 One character set contains 6-bit characters and provides 64 coded characters, the other
contains 7-bit characters and provides 128 coded characters. The two sets are compatible
in that they are logically related. This facilitates the conversion between the two sets.
1.2 Implementation
1.2.1 These character sets may be implemented in various media with logically related codes,
as appropriate. For example, this could include punched tapes, punched cards, magnetic
tapes and transmission channels, thus permitting interchange of data to take place
either indirectly by means of an intermediate recording in a physical medium, or by
local electrical connection of various units (such as input and output devices and com-
puters) or by means of data transmission equipment.
1.2.2 Other IS0 Recommendations describe the means of recording these character sets in
physical media and the means of encoding them for transmission while taking into
account the need for error checking *.
* For the implementation of codes
- on punched tape, see IS0 Recommendation R . . ., Representation of 6 and 7 bit coded character sets on
punched tape (at present at the stage of draft proposal);
- on punched cards, see IS0 Recommendation R . . . , Implementation of IS0 7 bit coded character set on 12 row
punched card (at present at the stage of draft proposal);
- on 7 and 9 track magnetic tape, see IS0 Recommendation R . . ., Implementation of the 6 and 7 bit coded
character sets on 7 track 112 in (12.7 mm) magnetic tape (at present Draft IS0 Recommendation No. 1320)
and IS0 Recommendation R . . . , Implementation of the 7 bit coded character set on 9 track 112 in (12.7 mm)
magnetic tape (at present Draft IS0 Recommendation No. 1321).
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IS0 / R 646 - 1967 (E)
2. TA
2.1 6-Bit set table
O O 1 1
O 1
O 1
O 1
2 3
SP O NUL P
1 IAiQ
F, (LF) @
2 I BËI R
3 C S
4 D T
F5 (CR) @ 5
E U
so 6 F V
---_-
0111 7 7 G w
SI
___?____
8 H X
1000 8
--_--
9
1001 9 I Y
*
1010 10 :@ J Z
1011 11
+ ;@ K ([I O
----___
1100 12 L (f)" @
-_~~-
1101 13
M (1)"
-____-
1110 14 > N ESC
q@k
@The controls CR and LF are intended for printer equipment 0 For international information interchange, 8 and € symbols d
not designate the currency of a given country. The use of the:
which requires separate combinations to return the carriage and
to feed a line. symbols combined with other graphic symbols to designate natioi
For equipment which uses a single control for a combined carriage al currencies may be the subject of other IS0 Recommendation
return and line feed operation,
O Reserved for National Use. These positions are primarily intendc
- in the 6-bit set table, the function F, will have the meaning of
for alphabetic extensions. If they are not required for that pu
" New Line " (NL). FI will then have the meaning of " Back-
pose, they may be used for symbols and a recommended choic
space " (BS);
is shown in parenthesis in some cases.
- in the 7-bit set table, the function FE, will have the meaning
Some restrictions are placed on the use of these characters on tl.
of '' New Line " (NL).
general telecommunication networks for international tran
These substitutions require agreement between the sender and
mission.
the recipient of the data.
@Positions 5/14, 6/0 and 7/14 of the 7-bit set table are normal
The use of this function " NL " is not allowed for international
provided for the diacritical signs " circumflex ", " grave accent
transmission on general telecommunication networks (Telex and
and " overline ". However, these positions may be used for othc
Telephone networks).
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iSO/ R 646 - 1967 (E)
VOTES
2.2 7-Bit set table
O Ir0 1 12 1
O 1 O 1
1 O 1 2 3 4 5 6 7
NUL (TC,)DLE SP O
O00 O
O01 1 rSOHF1 ‘TC,) STX DC, ~ ” ! @ 7 2
O10 2
‘TC,) ETX DC, Co O 3
O11 3
’TC3 EOT IDC, $0 4
100 4
101 5
110 6
111 7 (TClo)ETB ’ @ 7
BEL
H I X I h 1-x
O00 8
FE0 (BSI CAN ( 8
O01 9
FE,(HT) EM 1 9
FE,(LF)@ SUB * . 6)
O10 10
- (Ri
O11 11 FE, (VT) ESC +
-_-___
100 12 FE, (FF) IS4 (FS) 9 <
-
FE6(CR)@ IS3 (GS) - -
101 13
_~___
110 14 SO IS2 (RS) >
111 15
SI IS, (US) / ?
7 BIT SET TABLE
aphical symbols when it is necessary to have 8,9 or 10 positions O For international information interchange position 213 of the
7-bit set table has the significance of the symbol E. Within a
r national use.
country where there is no requirement for the symbol E, the
)r international information interchange, position 7/14 of the symbol # may be used in that position.
>it set table is used for the graphical symbol-(overline), the
@ If 10 and 11 as single characters are needed (for example, for
aphical representation of which may vary according to national
Sterling currency subdivision), they should take the place of
e to represent (tilde) or another diacritical sign provided that
“ colon ” (:) and “ semicolon ” (;) respectively. These substitu-
:re is no risk of confusion with another graphical symbol tions require agreement between the sender and the recipient of
:luded in the table. the data.
On the general te1ecomm;nication networks, the characters
ie graphics in positions 212, 217, 5/14 of the 7-bit set table have
“ colon ” and “ semicolon are the only ones authorized for
international transmission.
rpectively the significance of <‘ quotation mark ”, ‘‘ apostrophe ”
d “ upwards arrow ”; however, these characters take on the
O Either of the two sets of three symbols shown in these positions
mificance of the diacritical signs “ diæresis”, “acute accent” and
in the table may be chosen; the interpretation of the corresponding
:ircumflex accent ” when they precede or follow the “ back-
combinations requires agreement between the sender and the
ace ’’ character. recipient of the data.
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IS0 / R 646 - 1967 (E)
3. KEY
3.1 Controls
ACKNOWLEDGE
ACK
BEL BELL
BS BACKSPACE
CAN CANCEL
CARRIAGE RETURN
CR
DC DEVICE CONTROL
DEL DELETE
DLE DATA LINK ESCAPE
END OF MEDIUM
EM
ENQUIRY
ENQ
END OF TRANSMISSION
EOT
ESC ESCAPE
OF TRANSMISSION BLOCK
ETB END
END OF TEXT
ETX
F FUNCTION
FORMAT EFFECTOR
FE
FORM FEED
FF
FILE SEPARATOR
FS
GROUP SEPARATOR
GS
HORIZONTAL TABULATION
HT
INFORMATION SEPARATOR
IS
LF LINE FEED
NAK NEGATIVE ACKNOWLEDGE
NEW LINE
NL
NULL
NUL
RS RECORD SEPARATOR
SHIFT-IN
SI
SHIFT-OUT
so
START OF HEADING
SOH
SP SPACE
STX START OF TEXT
SUB SUBSTITUTE
SYNCHRONOUS IDLE
SYN
TRANSMISSION CONTROL
TC
UNIT SEPARATOR
us
VERTICAL TABULATION
VT
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E
IS0 / R 646 - 1967 (E)
3.2 Graphical Symbols
~~ ~ ~~~
Graphical Position in the
Name
code tables +
Representation
6-bit 7-b1t
A normally non-printing graphic character
010 210
-
Exclamation mark
211
-
Quotation mark. Diaeresis (note @)
212
Currency symbol S (note 0) 3/12
213
Currency symbol $ (note 0) 1/12
214
Percent 1/13
215
Ampersand 1/14
216
1/15
Apostrophe, Acute accent (note @)
217
Left parenthesis
018 218
Right parenthesis
019 219
0110 2/10
Asterisk
211 1
Plus sign 011 1
2/12
Comma 0112
Hyphen, minus sign 0113 2/13
Full stop (period) 0114 2/14
Solidus 0115 2/15
1/10 3/10
Colon
111 1 311 1
Semi-colon
1/12 3/12
Less than
1/13 3/13
Equals
3/14
1/14
Greater than
-
3/15
Question mark
-
Commercial at
410
311 1 5/11
Left square bracket
3/13 5/13
Right square bracket
-
5/14
Upwards arrow, Circumflex accent (note @)
-
5/15
Underline
-
Grave accent
610
-
7/14
Overline (note 0)
Notes @ @ @ see pages 6-7.
f See clause 4.1 page 10.
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IS0 / R 648 - 1967 (E)
4. EXPLANATORY NOTES
4.1 Numbering of the positions in the code tables
Within any one character the bits are identified by b,, b, . b,, where b, or b, is the highest
order, or most significant bit, and b, is the lowest order, or least significant bit.
If desired these may be given a numerical significance in the binary system, thus :
Bit identification: b, b, b6 b, b, b, b,
Significance : 64 32 16 8 4 2 i
In the code tables the columns and rows are identified by numbers written in binary and
decimal notations.
Any one position in a code table may be identified either by its bit pattern, or by its column
For instance, the position containing the figure 1 in the 7-bit set table
and row numbers.
may be identified :
- by its bit-pattern, e.g. O11 O001
- by its column and row numbers, e.g. 3/1.
4.2 Diacritical signs
In the 7 bit character set, some printing symbols may be designed to permit their use for the
composition of accented letters when necessary for general interchange of informat
...