ISO/IEC 24723:2010

INTERNATIONAL ISO/IEC
STANDARD 24723
Second edition
2010-08-01
Information technology — Automatic
identification and data capture
techniques — GS1 Composite bar code
symbology specification
Technologies de l'information — Techniques automatiques
d'identification et de capture des données — Spécifications de la
symbologie des codes à barres du Composant GS1

Reference number
©
ISO/IEC 2010
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ii © ISO/IEC 2010 – All rights reserved

Contents Page
Foreword .v
Introduction.vi
1 Scope.1
2 Normative references.1
3 Terms, definitions, abbreviated terms and mathematical operators .2
3.1 Terms and definitions .2
3.2 Abbreviated terms .3
3.3 Mathematical operators and notational conventions .3
4 Symbol description .3
4.1 Basic characteristics.3
4.2 Summary of additional features.4
4.3 Symbol structure .4
4.4 Supported component combinations.6
5 Source data encodation into a binary string .6
5.1 General .6
5.2 Encodation Method field.7
5.3 Compressed data field.7
5.4 General-purpose data compaction field.11
6 Error correction .15
7 Linear component requirements .15
7.1 General .15
7.2 EAN/UPC linear components .15
7.3 GS1 DataBar family linear components.16
7.4 GS1-128 components.18
8 CC-A component requirements .19
8.1 CC-A — General.19
8.2 Overview of the CC-A component .19
8.3 CC-A component structure.20
8.4 Symbol character structure.22
8.5 Base 928 compaction mode .24
8.6 Reference decode algorithm .25
9 CC-B component requirements .26
10 CC-C component requirements .27
11 Symbol dimensions.28
11.1 Minimum width of a module (X) .28
11.2 Linear component height.28
11.3 2D component row height (Y).28
11.4 Separator pattern and vertical separator bars .28
11.5 Quiet zones .29
12 Graphical requirements .29
12.1 General .29
12.2 Vertical alignment requirements.29
12.3 Horizontal alignment requirements .29
12.4 Human readable interpretation .30
13 Symbol quality .30
© ISO/IEC 2010 – All rights reserved iii

13.1 Linear component.30
13.2 2D component.30
13.3 Overall composite symbol grade .30
13.4 Additional pass/fail criteria.30
14 Transmitted data.30
14.1 General data transmission techniques .30
14.2 GS1-128 Composite symbols .31
14.3 GS1 DataBar Composite symbols.31
14.4 EAN/UPC Composite symbols .31
14.5 Symbol separator character .32
14.6 2D component escape mechanism character .32
14.7 Linear-only transmission mode .32
14.8 GS1-128 emulation.32
14.9 Examples of transmitted data.33
15 Application-defined parameters.33
Annex A (normative) Symbology identifiers .34
Annex B (normative) Parsing AI element strings .36
Annex C (normative) 2D component escape mechanism.38
Annex D (informative) Printing considerations.39
Annex E (informative) Base 928 radix conversions.42
Bibliography .45

iv © ISO/IEC 2010 – All rights reserved

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 24723 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 31, Automatic identification and data capture techniques.
This second edition cancels and replaces the first edition (ISO/IEC 24723:2006), which has been technically
revised.
© ISO/IEC 2010 – All rights reserved v

Introduction
Composite symbologies are a class of bar code symbology, the principal distinguishing feature of which is that
they comprise two, or more, components, each of which is a distinct symbol, but which contain a set of related
data. Typically one component is a linear symbol containing primary data, which can be read on its own in
some areas of the application. The other component(s) is a two-dimensional symbol containing supplementary
data which qualifies the primary message, and requiring all components to be read to extract the complete
message. The GS1 Composite symbology is one such symbology. The use of the symbology is intended to
comply with the GS1 General Specifications.
A GS1 Composite symbol consists of a linear component (encoding the item’s primary identification)
associated with an adjacent 2D component (encoding supplementary data, such as a batch number or
expiration date). The GS1 Composite symbol always includes a linear component so that the primary
identification is readable by all scanning technologies, and so that 2D imagers can use the linear component
as a finder pattern for the adjacent 2D component. The GS1 Composite symbol always includes a multi-row
2D component, for compatibility with linear and 2D imagers, and with linear and rastering laser scanners.
GS1 Composite symbols are intended for encoding identification numbers and data supplementary to the
identification in accordance with the GS1 General Specifications. The administration of the numbering system
by GS1 ensures that identification codes assigned to particular items are unique world-wide and that they and
the associated supplementary data are defined in a consistent way.

vi © ISO/IEC 2010 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 24723:2010(E)

Information technology — Automatic identification and data
capture techniques — GS1 Composite bar code symbology
specification
1 Scope
This International Standard defines the requirements for the GS1 Composite symbology. It specifies the GS1
Composite symbology characteristics, data character encodation, symbol formats, dimensions and print
quality requirements, error correction rules, and reference decoding algorithms. For those linear and 2D
components of GS1 Composite symbols with published symbology specifications, those published
specifications apply, except as specifically noted in this International Standard.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC 15415, Information technology — Automatic identification and data capture techniques — Bar code
print quality test specification — Two-dimensional symbols
ISO/IEC 15416, Information technology — Automatic identification and data capture techniques — Bar code
print quality test specification — Linear symbols
ISO/IEC 15417, Information technology ─ Automatic identification and data capture techniques ─ Code 128
bar code symbology specification
ISO/IEC 15420, Information technology ─ Automatic identification and data capture techniques ─ EAN/UPC
bar code symbology specification
ISO/IEC 15438, Information technology — Automatic identification and data capture techniques — PDF417
bar code symbology specification
ISO/IEC 19762-1, Information technology — Automatic identification and data capture (AIDC) techniques —
Harmonized vocabulary — Part 1: General terms relating to AIDC
ISO/IEC 19762-2, Information technology — Automatic identification and data capture (AIDC) techniques —
Harmonized vocabulary — Part 2: Optically readable media (ORM)
ISO/IEC 24728, Information technology — Automatic identification and data capture techniques —
MicroPDF417 bar code symbology specification
GS1 General Specifications (GS1, Brussels, Belgium)
© ISO/IEC 2010 – All rights reserved 1

3 Terms, definitions, abbreviated terms and mathematical operators
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 19762-1, ISO/IEC 19762-2 and
the following apply.
3.1.1
2D component
CC
two-dimensional portion of a GS1 Composite symbol, which encodes supplemental information about an item,
such as its lot number or expiration date
3.1.2
AI element string
character string containing an application identifier followed by its associated data field
3.1.3
CC-A
2D component that is a structural variant of MicroPDF417
NOTE 1 CC-A components can be autodiscriminated from MicroPDF417 symbols, because CC-A components have a
unique Rotation of 32 between any two adjacent Row Address Patterns.
NOTE 2 CC-A is one of the three choices for the 2D component in a symbol encoded in the GS1 Composite
symbology.
3.1.4
CC-B
2D component that is a MicroPDF417 symbol which begins with PDF417 codeword 920, indicating
conformance with this International Standard
NOTE CC-B is one of the three choices for the 2D component in a symbol encoded in the GS1 Composite
symbology.
3.1.5
CC-C
2D component that is a PDF417 symbol which begins with PDF417 codeword 920, indicating conformance
with this International Standard
NOTE CC-C is one of the three choices for the 2D component in a symbol encoded in the GS1 Composite
symbology.
3.1.6
linear component
linear portion of a GS1 Composite symbol, which encodes the primary identification of an item
3.1.7
linkage flag
indicator encoded in a GS1 DataBar or GS1-128 component to signal if a 2D component accompanies the
linear component
3.1.8
RAP Rotation
difference between the number designating a Center or Right Row Address Pattern and the number
designating the nearest Row Address Pattern to the left, in the same row of a MicroPDF417 symbol, or a
CC-A or CC-B component
2 © ISO/IEC 2010 – All rights reserved

3.1.9
Row Address Pattern
RAP
one of a set of patterns made up of three bars and three spaces occupying ten modules, that serve both as
start or stop patterns and as row indicators in a MicroPDF417 symbol, or a CC-A or CC-B component
3.1.10
separator pattern
pattern between the linear and 2D components of a GS1 Composite symbol
3.1.11
symbol separator character
non-data character that is used to break the transmitted data string into separate transmissions, each
beginning with the appropriate symbology identifier prefix
3.2 Abbreviated terms
AI Application Identifier
3.3 Mathematical operators and notational conventions
For the purposes of this document, the following mathematical operators apply.
div integer division operator which discards the remainder
mod integer remainder after integer division
The following ISO notational conventions are used.
0,2 a comma between digits separates the integer from the decimal fraction (e.g. 0,2 equals 2/10)
except when used as an (n,k) designation
12 345 a space between digits indicates factors of a thousand
4 Symbol description
4.1 Basic characteristics
A GS1 Composite symbol consists of a linear component associated with an adjacent 2D component. The
characteristics of the GS1 Composite symbology are:
a) Encodable character set:
1) Both linear and 2D components encode a subset of ISO/IEC 646, consisting of the upper and
lowercase letters, digits, and 21 selected punctuation characters.
2) The function character FNC1 and a Symbol Separator character.
b) Symbol character structure: various edge-to-similar-edge decodable symbol characters are used, in
accordance with the selected Linear and 2D components of the symbol.
c) Code type:
1) Linear component: continuous, linear bar code symbology.
2) 2D component: continuous, multi-row bar code symbology.
© ISO/IEC 2010 – All rights reserved 3

d) Maximum numeric data capacity (including implied application identifiers and calculated check digits
where appropriate, but not including any encoded FNC1 characters):
1) Linear component:
i) GS1-128: up to 48 digits
ii) EAN/UPC: UPC-A, EAN-8, or EAN-13 (12, 8, or 13 digits respectively)
iii) GS1 DataBar Expanded: up to 74 digits, see note
NOTE The GS1 DataBar Expanded data capacity depends on the encodation method. The maximum is
74 digits for (01) + other AI's, the maximum is 70 digits for any AI's, and the maximum is 77 digits for (01) +
(392x) + any AI's.
iv) Other GS1 DataBar: 16 digits
2) 2D component:
i) CC-A: up to 56 digits
ii) CC-B: up to 338 digits
iii) CC-C: up to 2 361 digits
e) Error detection and correction:
1) Linear component: one check character for error detection.
2) 2D component: a fixed or variable number of Reed-Solomon error correction codewords, depending
upon the specific 2D component.
f) Character self-checking: yes.
g) Bi-directionally decodable: yes.
4.2 Summary of additional features
The following is a summary of additional GS1 Composite symbology features:
a) Data compaction: the 2D components utilize a bit-oriented compaction mode, designed to encode
efficiently data using application identifiers.
b) Component linkage: the 2D component of each GS1 Composite symbol contains a linkage flag, which
indicates to the reader that no data shall be transmitted unless the associated linear component is also
scanned and decoded. All linear components except EAN/UPC also contain an explicit linkage flag.
c) GS1-128 emulation: readers set to the GS1-128 emulation mode transmit the data encoded within the
GS1 Composite symbol as if the data were encoded in one or more GS1-128 symbols.
d) 2D component escape mechanism: a mechanism to support future applications which require data
content beyond the ISO/IEC 646 subset encodable in the standard form of the GS1 Composite
symbology.
4.3 Symbol structure
Each GS1 Composite symbol consists of a linear component and a multi-row 2D component. The
2D component should nominally be printed with the same X dimension as the linear component. The
2D component is printed above the linear component (as defined in 12.2 and 12.3).
4 © ISO/IEC 2010 – All rights reserved

To facilitate printing the two components independently, 12.2 and 12.3 permit relative positional variation
between the two components. A bar code reader should not use the relative locations of the components
shown in the illustrations of GS1 Composite symbols in this specification to predict the exact location of the 2D
component from the location of the linear component.
The linear component is one of:
a) a member of the EAN/UPC symbology (EAN-13, EAN-8, UPC-A, or UPC-E, which may include an add-on
symbol, in accordance with ISO/IEC 15420),
b) a member of the GS1 DataBar symbology family,
c) GS1-128.
The choice of linear component determines the name of the GS1 Composite symbol, such as an EAN-13
Composite symbol, or a GS1-128 Composite symbol.
The 2D component (abbreviated as CC) is chosen based on the selected linear component, and on the
amount of supplementary data to be encoded. The three 2D components, listed in order of increasing
maximum data capacity, are:
a) CC-A, a variant of MicroPDF417, designed for efficient encoding of supplemental application identifier
data,
b) CC-B, a MicroPDF417 symbol with a codeword of 920 in the first data codeword position as a linkage flag,
and denoting GS1 data compaction, and
c) CC-C, a PDF417 symbol with a codeword of 920 in the first data codeword position as a linkage flag, and
denoting GS1 data compaction.
Figure 1 — A GS1 DataBar Limited Composite symbol
Figure 1 illustrates a GS1 DataBar Limited Composite symbol which utilizes a 4-row CC-A component as its
2D component. The GS1 DataBar Limited component in Figure 1 identifies the product as
“0113112345678906”, and the CC-A component encodes the expiration date and lot number (as
“1701061510A123456”). The human-readable interpretation of the data in the symbols would be shown, if
present, as “(01)13112345678906” and “(17)010615(10)A123456” respectively.

Figure 2 — A GS1-128 Composite symbol
Figure 2 illustrates a GS1-128 Composite symbol which utilizes a 5-row CC-C component as its 2D
component. The GS1-128 component in Figure 2 identifies the product as “0193812345678901”, and the
CC-C component encodes the lot number and deliver to location number (as
“10ABCD1234564103898765432108”). The human-readable interpretation of the data in the symbols
would be shown, if present, as “(01)93812345678901” and “(10)ABCD123456(410)3898765432108”
respectively.
© ISO/IEC 2010 – All rights reserved 5

4.4 Supported component combinations
Based upon the width of the linear component, a choice of “best-fit” 2D component is specified. Table 1 lists
all of the permissible combinations.
Table 1 — Permissible combinations of linear and 2D components
Linear component CC-A/CC-B CC-C
UPC-A and EAN-13 Yes (4-columns) No
EAN-8 Yes (3-columns) No
UPC-E Yes (2-columns) No
GS1-128 Yes (4-columns) Yes (variable width)
GS1 DataBar Omnidirectional Yes (4-columns) No
GS1 DataBar Stacked Yes (2-columns) No
GS1 DataBar Stacked Omnidirectional Yes (2-columns) No
GS1 DataBar Limited Yes (3-columns) No
GS1 DataBar Expanded Yes (4-columns) No
GS1 DataBar Expanded Stacked Yes (4-columns) No
In all cases where a CC-A component is shown in the table, the printing software shall automatically use a
CC-B component (of the same number of columns) when the data to be encoded exceeds the maximum
capacity of the CC-A or other means shall be provided to enable the correct selection of CC-A or CC-B to suit
the length of the data. The presence of an add-on symbol shall not affect the choice of 2D component. When
the linear component is GS1-128, either CC-A/CC-B or CC-C may be used; see 7.3.
5 Source data encodation into a binary string
5.1 General
The user data to be encoded into a 2D component shall always consist of application identifiers and data
fields that comply with the data standard of the GS1 General Specifications. The GS1-128 rules for
concatenation of AI element strings, such as the termination of a variable-length string by a FNC1 character,
shall be followed when encoding a 2D component.
Before encoding a 2D component, the given data string is encoded into a binary string, where data characters
are represented with a variable number of bits. The resulting binary string consists of two or three binary fields.
The fields are:
a) Encodation Method (see 5.2),
b) compressed data (see 5.3), and
c) general-purpose data compaction (see 5.4).
The Encodation Method is always encoded as the first field (see 5.2). One or both of the other fields are also
encoded in a 2D component. When both are present they are encoded in the order shown above.
The compressed data field efficiently encodes data using specific AIs, such as date and lot number or data
using AI 90 and serial numbers (see 5.3).
The general-purpose compaction field can encode data using any combination of AIs (see 5.4).
In the text of this clause, bit fields will be indicated by their binary values enclosed in double quotation marks.
6 © ISO/IEC 2010 – All rights reserved

5.2 Encodation Method field
The Encodation Method field consists of one or two bits. It occupies the first bits in the encoded binary data. It
defines whether the symbol is a general-purpose symbol or begins with an application-oriented compressed
data field (such as for efficient representation of expiration date and lot number AI element strings). The
Encodation Method field is defined in Table 2.
Table 2 — Encodation Method field
Encodation
Method field Description
bits
0 AI element string data using general-purpose data compaction
10 Date, lot number, and other AI element strings
11 AI 90 ( containing alphanumeric data) optionally followed by other AI element strings
An Encodation Method field of “0” is directly followed by AI data encoded using general-purpose data
compaction (see 5.4). The encoded data starts with the first application identifier and its element string data,
optionally followed by one or more AI element strings.
An Encodation Method field of “10” or “11” is directly followed by a compressed data field, optionally followed
by a general-purpose data compaction field (see 5.4).
5.3 Compressed data field
If the Encodation Method field is other than a single “0” bit, this indicates the presence of a field of
compressed data. The compression is specified to encode the data of specific AI element strings efficiently.
An Encodation Method field of “10” (see 5.3.1) is directly followed by a compressed data field suited for
marking pharmaceuticals and many other small items requiring an Expiration or Production Date and/or Lot
number. An Encodation Method field of “11” (see 5.3.2) is directly followed by a compressed data field suited
for many applications for marking small products with alphanumeric data. It may be necessary to sort the AI
element strings into the required sequence in order to benefit from the applicable Encodation Method.
5.3.1 Encodation Method field “10” — date and lot number
This Encodation Method may be used if the element strings of AI 11 followed by AI 10, AI 17 followed by AI 10,
or the single AIs 10, 11 or 17 occur at the start of the data message to be encoded. An Encodation Method
field of “10” is followed by a compressed date field (which may be empty), an optional lot number, possibly
followed by other AI element strings (which if present, are encoded using general-purpose data compaction).
The compressed date field following the “10” Encodation Method field consists of either:
a) A 17-bit field, consisting of:
1) a 16-bit value encoding 0 to 38 399 for YYMMDD (year, month, and day) according to the equation
(YY x 384) + ((MM-1) x 32) + (DD)
2) followed by a single bit indicating the type of date: “0” for Production Date (AI 11) or “1” for Expiration
Date (AI 17)
or:
b) A 2-bit date field of “11” which is a flag indicating that no date was encoded.
NOTE 1 The 16-bit date values 0-38 399 will start with “0” or “10” so that “11” is a unique two-bit flag.
© ISO/IEC 2010 – All rights reserved 7

NOTE 2 The YYMMDD format for data is required to comply with GS1 application specifications. Separate algorithms
are provided to convert the date into its format of CCYYMMDD.
The date is encoded by stripping the two-digit AI 11 or AI 17 from the date element string and encoding the
remaining six digits into 16 bits using the equation above. For AI 11, the next bit is “0”; for AI 17 the next bit is
“1”. If there was no date, a 2-bit field of “11” is encoded instead of the 17-bit field.
If a lot number directly follows the date element string, the two-digit AI 10 is stripped from the lot number
element string, and the remainder of the lot number element string is encoded using general-purpose data
compaction, directly following the date field. If more AI element strings follow the lot number, a FNC1
separates the lot number data from the next AI element string to be encoded.
If a lot number does not directly follow the date element string, a FNC1 is encoded following the date element
string, even if no more data follows the date element string (this FNC1 shall not be transmitted by the
decoder). If more data follows, it is encoded using general-purpose data compaction beginning with the digits
of the next AI.
The decoder shall reconstruct the AI element strings from a compressed data field using an Encodation
Method field of “10” according to the following procedure:
a) If the bits “11” follow the method “10”, no date is encoded, and the decoder shall insert the two-digit AI 10
before the remaining general-purpose data compaction field is decoded.
b) Otherwise, the 6-digit date shall be extracted according to the above equation. If the seventeenth bit is “0”,
an AI 11 for production date is added as a prefix by the decoder. If the seventeenth bit is “1”, an AI 17 for
expiration date is added. If the first encoded data character following the date field is FNC1, there is no lot
number (this FNC1 shall not be transmitted by the decoder). Otherwise the decoder shall insert the two-
digit AI 10 before the remaining general-purpose data compaction field is decoded.
5.3.2 Encodation Method field of “11” — AI 90
This Encodation Method may be used if an element string with an AI 90 occurs at the start of the data
message, and if the data field following the two-digit AI 90 starts with an alphanumeric substring which
complies with a specific format. The format of the alphanumeric data that can be used in this compaction
method is 0, 1, 2, or 3 digits (strings with leading zeros do not comply with the required format) followed by an
uppercase alphabetic character.
An Encodation Method field of “11” is followed by a compressed data field which includes the encoded
special-format alphanumeric string, followed by the remainder of its data field, optionally additional
compressed data fields, and optionally additional AI element strings.
The compressed data field following the “11” Encodation Method consists of the following:
a) One or two bits indicating the starting data encodation scheme used for the remainder of the AI 90 data
field. A “0” indicates Alphanumeric encodation, a “10” indicates Numeric encodation and an “11” indicates
Alpha encodation (see 5.3.3).
b) One or two bits indicating the absence or presence, respectively, of specific AIs after the first FNC1
(which terminates the AI 90 element string, unless no further data is encoded). “0” indicates that either no
more data is encoded, or that the remaining data is encoded according to general-purpose data
compaction rules. Otherwise, the AI of the next element string will not be explicitly encoded. “10” indicates
that an AI 21 follows, and “11” indicates that an AI 8004 follows.
c) Nine or 20 bits encoding the 1 to 4 characters of the alphanumeric string that followed the AI 90 in the
source message, encoded as follows:
1) Convert the numeric portion of the alphanumeric string to a value. If the string contains no numeric
digits, the value is 0.
8 © ISO/IEC 2010 – All rights reserved

2) If the numeric value is less than 31, and if the uppercase alphabetic letter is one of those listed in
Table 3, encode the numeric value as a five-bit binary string. Then convert the uppercase alphabetic
character to four bits of binary data using Table 3 and encode these as a four-bit binary string.
3) Otherwise encode a five-bit string “11111”, followed by a 10-bit string representing the value of the
numeric digits, followed by a five-bit string representing the ASCII value of the letter minus 65 (where
“A” is encoded as “00000”, and “Z” is encoded as “11001”).
Table 3 — Supported uppercase alphabetic letters
Letter Binary Data Letter Binary Data
B 0000 P 1000
D 0001 Q 1001
H 0010 R 1010
I 0011 S 1011
J 0100 T 1100
K 0101 V 1101
L 0110 W 1110
N 0111 Z 1111
During encoding, the AI 90 and the alphanumeric string are stripped from the first AI element string. The next
two to four bits specify the starting encodation scheme for the remainder of the element string, and whether an
AI 21 or AI 8004 element string follows the AI 90 element string. Then the compacted alphanumeric string is
encoded in the next nine or twenty bits. The remainder of the AI 90 element string is encoded using either
general-purpose data compaction starting in Alphanumeric or Numeric schemes, or the Alpha encodation
scheme, as specified by the encodation scheme bit field. The AI element string data is terminated by an
encoded FNC1, unless it is the last AI element string of the input data.
If an AI 21 or AI 8004 element string follows the AI 90 element string, the 21 or 8004 is stripped from the
element string, and the remainder of the AI element string is encoded, starting in the default Numeric
encodation scheme of general-purpose data compaction. If the AI 90 element string is encoded using the
numeric encodation scheme when the FNC1 is encountered, the first digit of the following AI element string
may be encoded with the FNC1 in the same seven bits of the numeric encodation scheme. Any additional
data is then encoded.
The decoder shall reconstruct the AI element strings from a “11” compressed data field according to the
following procedure.
a) The 2-digit AI 90 is inserted to start the decoded data string.
b) The first two to four bits are decoded to determine the encodation scheme and whether a specific element
string of AI 21 or AI 8004 follows the AI 90 element string.
c) The next five bits are decoded to determine the number of digits in the alphanumeric string and their
value.
1) If the value of the five bits is less than 31, these five bits are decoded to determine the number of
digits and their value (discarding any leading zeros), and the next four bits are decoded using
Table 3 to determine the uppercase alphabetic character in the alphanumeric string.
2) Otherwise, the ten bits following the “11111” are decoded to determine the number of digits and their
value (discarding any leading zeros); and the next five bits are decoded to determine the uppercase
letter in the alphanumeric string.
d) Append the alphanumeric string to the decoded data string.
© ISO/IEC 2010 – All rights reserved 9

e) The bits up to the first FNC1 are decoded starting with the encodation scheme specified by the first one
or two bits.
f) If the special-AI bit field was “0”, proceed to the next step below. Otherwise, the bit field was “10” or “11”,
add the two-digit AI 21 or the four-digit AI 8004, respectively, to the decoded data string directly following
the last decoded FNC1.
NOTE the leading digit of the data field following AI element string’s data field may have already been decoded
if it was paired with the FNC1 in Numeric encodation.
g) Starting from Numeric encodation, continue decoding the general-purpose field following the FNC1
character.
The Symbol Separator character also can terminate an AI element string. It is processed in the same way as
FNC1 as described in this clause, except that it cannot be encoded in Numeric or Alpha compaction schemes.
5.3.3 Alpha encodation
Alpha encodation, available only from within the “11” Encodation Method as specified in 5.3.2, encodes
uppercase Alphabetic characters into 5 bits each, and encodes digits into 6 bits each. This mode also includes
a 5-bit FNC1/numeric latch character. The mode remains in effect until the next FNC1 (encoded as the
FNC1/numeric latch) or the end of the data message. Each character is encoded as shown in Table 4.
If, after all of the source message has been encoded in Alpha encodation and any bits remain in the symbol
capacity, then a FNC1/numeric latch shall be encoded. This FNC1 is truncated if fewer than five bits remain in
the symbol. If necessary, the remaining symbol capacity shall be padded as described in 5.4.4. The reader
shall not transmit this trailing FNC1.
Table 4 — Alpha encodation
Character(s) ASCII value(s) Encoded value Encoded binary data
A to Z 65 to 90 ASCII - 65 (5-bit) 00000 to 11001
0 to 9 48 to 57 ASCII + 4 (6 bit) 110100 to 111101
FNC1/numeric latch 31 (5-bit) 11111
The Alpha mode should be used in the AI 90 compaction method if:
a) The remaining data characters up to the next FNC1 (or to the end of the message if there is no FNC1)
are either digits or uppercase letters, and
b) The number of letters is greater than the number of digits.
The data is encoded by appending the variable length binary data for each character, up to and including the
next FNC1 or the end of the message.
The encoded bit field is decoded by first examining the first five bits in the field following the previously
decoded character or initially at the start of the field.
a) If the value of these five bits is less than 26, it is one of the 5-bit characters in the set; decode these 5 bits
as an uppercase letter according to Table 4.
b) If the value of the five bits is 31, then it is a 5-bit FNC1/numeric latch character.
c) Otherwise, decode the five bits together with the following bit as a digit according to Table 4.
10 © ISO/IEC 2010 – All rights reserved

5.4 General-purpose data compaction field
The general-purpose data compaction field is preceded either by an Encodation Method field of “0”, or by a
compressed data field. It encodes AI element string data into a binary field, using a combination of three
encodation schemes:
a) Numeric encodation is used for numbers and FNC1 characters, requiring 3,5 bits per encoded character;
b) Alphanumeric encodation is used for a mix of numbers, uppercase letters, and a subset of punctuation
characters, requiring 5 bits per digit or FNC1 character, and 6 bits per letter or punctuation character;
c) ISO/IEC 646 encodation is used for a mix of uppercase and lowercase letters, numbers, and most
punctuation characters, requiring 5 bits per digit or FNC1, 7 bits per letter, and 8 bits per punctuation
character.
General-purpose data compaction is used to encode the AI element strings other than those specifically
encoded using one of the compressed data Encodation Methods defined in 5.3. The general-purpose data
compaction field, if present, is the last field in the symbol. Once all of the data has been processed using
general-purpose data compaction scheme(s), the general-purpose encoding process concludes with the
padding procedure described in 5.4.4.
5.4.1 Numeric encodation
Numeric encodation is the default encodation scheme that is in effect at the start of the general-purpose data
compaction field. It encodes two digits or a digit and FNC1 character (in either order) in seven bits. These
seven bits represent the decimal value V, determined by:
V = (11 D ) + D + 8
1 2
where D and D are the first and second digit values or FNC1 value (FNC1 is assigned a decimal value
1 2
of 10). The decimal value V ranges from 8 to 127 corresponding to the binary strings “0001000” to “1111111”
(two FNC1 characters cannot be encoded in seven bits). A binary sequence of “0000” at the start of the field
or
...