ISO/IEC 24724:2006

Information technology - Automatic identification and data capture techniques - Reduced Space Symbology (RSS) bar code symbology specification

The GS1 Reduced Space Symbology (RSS) family contains three linear symbologies (RSS-14, RSS Limited and RSS Expanded) to be used with the GS1 system. The use of the symbology is intended to comply with the GS1 application guidelines as defined in the GS1 General Specifications. RSS-14 encodes the full 14-digit GS1 item identification in a linear symbol that can be scanned omnidirectionally by suitably programmed point-of-sale scanners. RSS Limited encodes a 14-digit GS1 item ?identification with Indicator digits of zero or one in a linear symbol for use on small items that will not be scanned at the point-of-sale. RSS Expanded encodes GS1 item identification plus supplementary AI element strings such as weight and 'best before' date in a linear symbol that can be scanned omnidirectionally by suitably programmed point-of-sale scanners. RSS-14 Stacked is a variation of the RSS-14 symbology that is stacked in two rows and is used when the normal symbol would be too wide for the application. It comes in two versions, a truncated version used for small item marking applications and a taller omnidirectional version which is designed to be read by omnidirectional scanners. RSS Expanded can also be printed in multiple rows as a stacked symbol. Any member of the RSS family can be printed as a stand-alone linear symbol or as part of an EAN.UCC Composite symbol with an accompanying two-dimensional component printed above the RSS linear component. GS1 RSS bar code symbols are intended for encoding identification numbers and data supplementary to the identification. The administration of the numbering system by EAN and UCC ensures that identification codes assigned to particular items are unique worldwide and that they and the associated supplementary data are defined in a consistent way. The major benefit for the users of the GS1 system is the availability of uniquely defined identification codes and supplementary data formats for use in their trading transactions. ISO/IEC 24724:2006 defines the requirements for the RSS symbology family. It specifies the characteristics of the RSS symbology family, data character encodation, symbol formats, dimensions, print quality requirements, error detection, and decoding algorithms. For EAN.UCC Composite symbols, ISO/IEC 24723 defines the two-dimensional component.

Technologies de l'information — Techniques automatiques d'identification et de capture des données — Spécifications de la symbologie des codes à barres de la symbologie d'espace réduit (RSS)

General Information

• Status: Withdrawn
• Publication Date: 24-Oct-2006
• Withdrawal Date: 24-Oct-2006
• ICS: 01.080.50 - Graphical symbols for use on information technology and telecommunications technical drawings and in relevant technical product documentation
• ICS: 35.040 - Information coding
• ICS: 35.040.50 - Automatic identification and data capture techniques
• Technical Committee: ISO/IEC JTC 1/SC 31 - Automatic identification and data capture techniques
• Drafting Committee: ISO/IEC JTC 1/SC 31/WG 1 - Data carrier
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 29-Mar-2011
• Completion Date: 30-Oct-2025

Relations

• Revised: ISO/IEC 24724:2011 - Information technology - Automatic identification and data capture techniques - GS1 DataBar bar code symbology specification
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 24724
First edition
2006-11-01
Information technology — Automatic
identification and data capture
techniques — Reduced Space Symbology
(RSS) bar code symbology specification
Technologies de l'information — Techniques d'identification
automatique et de capture des données — Spécifications de
la symbologie des codes à barres de la symbologie d'espace réduit
(RSS)
Reference number
©
ISO/IEC 2006
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ii © ISO/IEC 2006 – 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 Types of RSS symbol . 3
4.2 Symbology characteristics . 3
4.3 Summary of additional features . 4
4.4 Symbol structure . 4
5 Symbol requirements for RSS-14. 5
5.1 Basic characteristics. 5
5.2 Symbol structure . 5
5.2.1 Data character structure . 6
5.2.2 Data character value. 6
5.2.3 Symbol value. 8
5.2.4 Finder patterns. 9
5.2.5 Reference decode algorithm . 10
5.3 Special RSS-14 formats for specific applications . 12
5.3.1 RSS-14 Truncated format. 12
5.3.2 RSS-14 two-row formats . 13
6 Symbol requirements for RSS Limited.14
6.1 Basic characteristics. 14
6.2 Symbol structure . 15
6.2.1 Data character structure . 15
6.2.2 Data character value. 15
6.2.3 Symbol value. 16
6.2.4 Check character. 17
6.2.5 Finder pattern. 17
6.2.6 Reference decode algorithm . 18
7 Symbol requirements for RSS Expanded . 19
7.1 Basic characteristics. 19
7.2 Symbol structure . 19
7.2.1 Overall symbol structure . 19
7.2.2 Symbol character structure . 20
7.2.3 Symbol character value . 21
7.2.4 Symbol binary value. 22
7.2.5 Data encodation. 22
7.2.6 Check character. 31
7.2.7 Finder pattern. 32
7.2.8 RSS Expanded Stacked . 34
7.2.9 Reference decode algorithm . 35
8 Symbol quality . 37
8.1 Linear symbology parameters. 37
8.2 Additional pass/fail criteria. 37
© ISO/IEC 2006 – All rights reserved iii

8.3 Stacked symbols. 37
9 Transmitted data . 37
10 Human readable interpretation. 38
11 Minimum width of a module (X). 38
12 Application-defined parameters . 38
Annex A (normative) Check digit calculation . 39
Annex B (normative) C-language element width encoder and decoder. 40
Annex C (normative) RSS Limited check character element widths . 44
Annex D (normative) Splitting long RSS Expanded symbols for UCC/EAN emulation mode. 47
Annex E (informative) Symbol elements . 48
Annex F (informative) Encoding examples . 52
Annex G (informative) C-language element width decoder . 57
Annex H (informative) Considerations to minimize misreads . 60
Annex I (informative) Printing considerations. 61
Annex J (informative) Reduced Space Symbology — Summary of Characteristics . 64
Bibliography . 65

iv © ISO/IEC 2006 – 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 24724 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 31, Automatic identification and data capture techniques.

© ISO/IEC 2006 – All rights reserved v

Introduction
The GS1 Reduced Space Symbology (RSS) family contains three linear symbologies (RSS-14, RSS Limited
and RSS Expanded) to be used with the GS1 system. The use of the symbology is intended to comply with
the GS1 application guidelines as defined in the GS1 General Specifications.
RSS-14 encodes the full 14-digit GS1 item identification in a linear symbol that can be scanned
omnidirectionally by suitably programmed point-of-sale scanners. RSS Limited encodes a 14-digit GS1
item identification with Indicator digits of zero or one in a linear symbol for use on small items that will not be
scanned at the point-of-sale. RSS Expanded encodes GS1 item identification plus supplementary AI element
strings such as weight and “best before” date in a linear symbol that can be scanned omnidirectionally by
suitably programmed point-of-sale scanners.
RSS-14 Stacked is a variation of the RSS-14 symbology that is stacked in two rows and is used when the
normal symbol would be too wide for the application. It comes in two versions, a truncated version used for
small item marking applications and a taller omnidirectional version which is designed to be read by
omnidirectional scanners. RSS Expanded can also be printed in multiple rows as a stacked symbol.
Any member of the RSS family can be printed as a stand-alone linear symbol or as part of an EAN.UCC
Composite symbol with an accompanying 2D component printed above the RSS linear component.
GS1 RSS bar code symbols are intended for encoding identification numbers and data supplementary to the
identification. The administration of the numbering system by EAN and UCC ensures that identification codes
assigned to particular items are unique worldwide and that they and the associated supplementary data are
defined in a consistent way. The major benefit for the users of the GS1 system is the availability of uniquely
defined identification codes and supplementary data formats for use in their trading transactions.

vi © ISO/IEC 2006 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 24724:2006(E)

Information technology — Automatic identification and data
capture techniques — Reduced Space Symbology (RSS) bar
code symbology specification
1 Scope
This International Standard defines the requirements for the RSS symbology family. It specifies the
characteristics of the RSS symbology family, data character encodation, symbol formats, dimensions, print
quality requirements, error detection, and decoding algorithms.
For EAN.UCC Composite symbols, ISO/IEC 24723 defines the 2D component.
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 646, Information technology — ISO 7-bit coded character set for information interchange
ISO 4217, Codes for the representation of currencies and funds
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 — Bar code
symbology specification — Code 128
ISO/IEC 15420, Information technology — Automatic identification and data capture techniques — Bar code
symbology specification — EAN/UPC
ISO/IEC 15424, Information technology — Automatic identification and data capture techniques — Data
Carrier Identifiers (including Symbology Identifiers)
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 24723, Information technology — Automatic identification and data capture techniques — EAN.UCC
Composite bar code symbology specification
GS1 General Specifications (GS1, Brussels, Belgium)
© ISO/IEC 2006 – 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.
NOTE For terms which are defined below and in ISO/IEC 19762, the definitions given below apply.
3.1.1
2D component
two-dimensional portion of an EAN.UCC 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
EAN/UPC
bar code symbology specified in ISO/IEC 15420
3.1.4
encodation methods
compaction schemes used by RSS Expanded and 2D components to encode commonly used AI element
strings in binary strings that are shorter than would be required using general data compaction for the
symbology
3.1.5
Indicator digit
leading digit of a GTIN-14 item identification number used to differentiate multiple levels of packaging or to
indicate a variable measure item
3.1.6
linear component
linear portion of an EAN.UCC Composite symbol, which encodes the primary identification of an item
3.1.7
linkage flag
indicator encoded in an RSS or UCC/EAN-128 linear component to signal if a 2D component accompanies
the linear component
3.1.8
segment
minimum decodable portion of a bar code symbol, consisting, in RSS, of a symbol character and its adjacent
finder pattern
3.1.9
UCC/EAN-128
subset, specified in GS1 General Specifications, of Code 128 as defined in ISO/IEC 15417
3.1.10
voting
decoding technique whereby decoded segment values are saved along with a count of the number of times
they have been decoded
NOTE Voting is used for decoding RSS by segments such as when used with omnidirectional scanning.
2 © ISO/IEC 2006 – All rights reserved

3.2 Abbreviated terms
AI Application Identifier (see ISO/IEC 15418)
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 numbers represents a decimal value (e.g. 0,2 equals 2/10) except when used in
subscripts or as an (n,k) designation
12 345 a space between digits indicates factors of a thousand
4 Symbol description
4.1 Types of RSS symbol
The RSS family consists of the following versions:
RSS-14
RSS-14 Truncated
RSS-14 Stacked
RSS-14 Stacked Omnidirectional
RSS Limited
RSS Expanded
RSS Expanded Stacked
The first group of RSS-14 configurations all contain four symbol characters in every symbol and have identical
encodation rules and structure.
The second group, RSS Limited, is structurally different, containing two symbol characters and uses different
encodation rules.
The third group, RSS Expanded, has yet another distinct symbology structure and set of encodation rules.
RSS-14, RSS-14 Stacked Omnidirectional, RSS Expanded, RSS Expanded Stacked are designed to be read
in segments by omnidirectional scanners.
Annex J contains a summary of characteristics of the RSS family of symbologies.
4.2 Symbology characteristics
The characteristics of the RSS family are:
a) Encodable character set:
1) RSS-14 group and RSS Limited: 0 through 9
2) RSS Expanded: a subset of ISO/IEC 646, consisting of the upper and lowercase letters, digits,
and 20 selected punctuation characters in addition to the special function character, FNC1
© ISO/IEC 2006 – All rights reserved 3

b) Symbol character structure: different (n,k) symbol characters are used for each member of the family,
where each symbol character is n modules in width and is composed of k bars and k spaces.
c) Code type: continuous, linear bar code symbology.
d) Maximum numeric data capacity (including implied application identifiers where appropriate, but not
including any encoded FNC1 characters):
1) RSS-14 group and RSS Limited: application identifier “01” plus a 14-digit numeric item
identification
2) RSS Expanded: 74 numeric or 41 alphabetic characters (see note)
NOTE The RSS Expanded data capacity depends on the encodation method. The maximum is 74 digits for
(01) + other AIs, the maximum is 70 digits for any AIs, and the maximum is 77 digits for (01) + (392x) + any AIs.
e) Error detection:
1) RSS-14 group: mod 79 checksum
2) RSS Limited: mod 89 checksum
3) RSS Expanded: mod 211 checksum
f) Character self-checking: yes.
g) Bidirectionally decodable: yes.
4.3 Summary of additional features
The following is a summary of additional RSS family features:
a) Data compaction: Each member of the family has data compaction methods optimized for the data strings
that they will encode. RSS Expanded is optimized for specific combinations of application identifiers that
are commonly used.
b) Component linkage: All RSS symbols include a linkage flag. If the linkage flag is clear, i.e. equal to 0,
then the RSS symbol stands alone. If the linkage flag is set, i.e. equal to 1, then a 2D component is
associated with the RSS family linear component and its separator pattern.
c) UCC/EAN-128 emulation: Readers set to the UCC/EAN-128 emulation mode transmit the data encoded
within the RSS family symbol as if the data were encoded in one or more UCC/EAN-128 symbols.
4.4 Symbol structure
Each RSS symbol contains outside guard patterns, symbol characters, and finder patterns. Every symbol
includes a method for error detection.
The guard patterns consist of two one-module wide elements forming either a bar/space or a space/bar pair at
each end of the symbol. RSS-14 Stacked and RSS Expanded Stacked symbols have guard patterns at the
ends of each row of the symbol. See Annex I.1 regarding printing considerations for exterior guard pattern
elements.
Every symbol has two or more data characters, each with an (n,k) structure. The data characters values are
combined mathematically to form the explicitly encoded data.
The finder pattern is a set of elements selected to be identifiable by the decoder so that the symbol can be
recognized and the relative position of the elements can be determined. Each symbol contains one or more
finder patterns. The finder patterns also function as the check character and/or segment identifiers.
4 © ISO/IEC 2006 – All rights reserved

All RSS symbols include a linkage flag. If the flag is set, the RSS linear component and its contiguous
separator pattern shall be aligned with a 2D component in accordance with ISO/IEC 24723. Normally the RSS
linear component, its contiguous separator pattern, and the 2D component are printed at the same time,
comprising a single EAN.UCC Composite symbol. It is possible however, to preprint an RSS linear component
with the linkage flag set in anticipation of a subsequent process in which the 2D component is added. Under
such circumstances the separator pattern shall be printed with the RSS linear component in accordance with
ISO/IEC 24723.
5 Symbol requirements for RSS-14
5.1 Basic characteristics
RSS-14 is a linear symbology capable of encoding 20 000 000 000 000 (2 × 10 ) values. These values are
expressed as 14 digits. The first digit is a linkage flag. The following 13 digits are data characters. The 13 data
characters plus an implied check digit form an GS1 14-digit item identification number including a leading
Indicator digit. Values 10 000 000 000 000 and above indicate that the linkage flag is set and therefore a 2D
component is present, e.g. value 10 001 234 567 890 encodes item 00012345678905 with the linkage flag
equal to 1.
RSS-14 can be scanned and decoded in four segments and then reconstructed. This facilitates
omnidirectional scanning. Figure 1 illustrates a stand-alone RSS-14 symbol (linkage flag equal to 0).

Figure 1 — RSS-14 symbol representing (01)20012345678909
NOTE The leading (01) is the implied application identifier and is not encoded in the symbol. The last digit, 9, is not
directly encoded in the symbol, but is a calculated mod 10 check digit. See Annex A for the check digit calculation.
Annex F.1 contains a complete example of encoding an RSS-14 symbol.
5.2 Symbol structure
An RSS-14 symbol, as shown in Figure 2, consists of eight regions (from left to right) comprising 96 modules:
a) a one module space and one module bar left guard pattern
b) four spaces and four bars with 16 modules comprising data character 1, (n,k) = (16,4)
c) three spaces and two bars with 15 modules comprising the left finder pattern
d) four bars and four spaces with 15 modules comprising data character 2, (n,k) = (15,4) (right to left)
e) four bars and four spaces with 15 modules comprising data character 4, (n,k) = (15,4)
f) three bars and two spaces with 15 modules comprising the right finder pattern (right to left)
g) four spaces and four bars with 16 modules comprising data character 3, (n,k) = (16,4) (right to left)
h) a one module space and one module bar right guard pattern
NOTE The data character elements are ordered toward the adjacent finder.
© ISO/IEC 2006 – All rights reserved 5

data data data data
left left right
right
character character character character
guard finder finder guard
1 2 4 3
pattern pattern
(16,4) (15,4) (15,4) (16,4)
Figure 2 — RSS-14 symbol representing (01)04412345678909
The total symbol contains 46 elements (bars and spaces) comprising 96 modules. Table E.1 in Annex E lists
all 46 elements of an RSS-14 symbol. An RSS-14 symbol intended for omnidirectional scanning shall have a
height greater than or equal to 33X (33 modules).
No quiet zones are required. The first and last elements may appear wider than one module without affecting
the symbol if the adjacent background area is the same “color” (light on the left or dark on the right).
5.2.1 Data character structure
Each of the four data characters has an (n,k) structure. The value of n is 16 for the first and third (outside)
data characters and 15 for the second and fourth (inside) data characters. The value of k is 4.
In Figure 2 the arrows show the ordering of element numbers within each character. The elements of the first
and fourth data characters are ordered from left to right and the elements of the second and third characters
are ordered from right to left, so that the data character elements are always ordered toward the adjacent
finder.
Each data character contains two subsets of odd- and even-numbered elements. The terms odd and even
refer to the ordinal number of the elements in each subset. For example the odd-numbered subset consists of
the first, third, fifth and seventh elements in each data character starting with the element farthest from the
adjacent finder pattern. In data characters one and two, the odd elements are spaces and the even elements
are bars. In data characters three and four, the odd elements are bars and the even elements are spaces.
5.2.2 Data character value
For each data character value, an algorithm assigns a pattern of element widths to the odd and even subsets.
The algorithm is given the number of elements, the number of modules, maximum element width, and whether
the subset can have all elements wider than one module. Annex B gives a C-language implementation of the
RSS-14 data character element generation algorithm.
5.2.2.1 Outside data character values
For the outside data characters 1 and 3, the valid even element combinations shall have at least one single-
module-wide element. The valid odd element subsets need not have a single-module-wide element. The even
element restriction insures that the data characters have unique edge-to-similar-edge (bar plus space and
space plus bar) module sums.
Table 1 shows the characteristics of the (16,4) subsets, listing the odd and even subset pairs in five groups.
Both subsets have an even number of modules. The widest element widths are specified so that the number
of modules in a pair of adjacent elements is never greater than nine. The total number of combinations of a
(16,4) character is 2 841. The (16,4) data character value V is calculated by:
D
V = (V × T ) + V + G
D ODD EVEN EVEN SUM
6 © ISO/IEC 2006 – All rights reserved

where T is the even subset total value, V is the odd subset value, V is the even subset value, and
EVEN ODD EVEN
G is the sum of the products of values for each previous group in Table 1. To encode a specific data
SUM
character of V :
D
V = (V – G ) div T
ODD D SUM EVEN
V = (V – G ) mod T
EVEN D SUM EVEN
For example a (16,4) data character with the value of 2 315 is to be encoded. From Table 1, the value of the
data character is in the range of Group 4, so G = 2 015 and T = 70. Using the above equations:
SUM EVEN
V = (2 315 – 2 015) div 70 = 300 div 70 = 4
ODD
V = (2 315 – 2 015) mod 70 = 300 mod 70 = 20
EVEN
The data character value 2 315 is in Group 4 (see Table 1). The data character is comprised of an odd subset
with 6 modules and a sequential value of V = 4 out of 10 (range 0 to 9) and an even subset with
ODD
10 modules and a sequential value of V = 20 out of 70 (range 0 to 69). Using the routines in Annex B, the
EVEN
odd element widths are {1 2 2 1} and the even element widths are {1 5 1 3} giving the data character element
widths of {1 1 2 5 2 1 1 3} as ordered towards the finder pattern (see Figure 2).
Table 1 — Outside data character (16,4) characteristics
Sum of Odd/even Odd/even Odd subset Even subset
Value range Group previous subset widest total values, total values,
groups, G modules elements T T
SUM ODD EVEN
0 to 160 1 0 12/4 8/1 161 1
161 to 960 2 161 10/6 6/3 80 10
961 to 2 014 3 961 8/8 4/5 31 34
2 015 to 2 714 4 2 015 6/10 3/6 10 70
2 715 to 2 840 5 2 715 4/12 1/8 1 126
5.2.2.2 Inside data character values
For the inside data characters 2 and 4, the valid odd element combinations shall have at least one single
module wide element. The valid even element subsets need not have a single-module-wide element. The odd
element restriction insures that the data characters have unique edge-to-similar-edge (bar plus space and
space plus bar) module sums.
Table 2 shows the characteristics of the (15,4) subsets, listing the odd and even subset pairs in four groups.
The odd subset has an odd number of modules and the even subset has an even number of modules. The
widest element widths are specified so that the number of modules in a pair of adjacent elements is never
greater than nine. The total number of combinations for a (15,4) character is 1 597. The range of allowed
values of the odd subset is restricted so that the innermost element (odd element number 1) will not exceed
4 modules.
Table 2 — Inside data character (15,4) characteristics
Sum of Odd/even Odd/even Odd subset Even subset
Value range Group previous subset widest total values, total values,
groups, G modules elements T T
SUM ODD EVEN
0 to 335 1 0 5/10 2/7 4 84
336 to 1 035 2 336 7/8 4/5 20 35
1 036 to 1 515 3 1 036 9/6 6/3 48 10
1 516 to 1 596 4 1 516 11/4 8/1 81 1
© ISO/IEC 2006 – All rights reserved 7

The (15,4) data character value V is calculated by:
D
V = (V × T ) + V + G
D EVEN ODD ODD SUM
where T is the odd subset total value, V is the even subset value, V is the odd subset value, and G
ODD EVEN ODD SUM
is the sum of the products of values for each previous group. To encode a specific data character of value V :
D
V = (V – G ) div T
EVEN D SUM ODD
V = (V – G ) mod T
ODD D SUM ODD
Note that the significance of the even and odd subsets is reversed in these calculations compared to the
(16,4) outside data characters.
5.2.3 Symbol value
The value of the symbol is formed by combining the values of the left data character pairs and the right data
character pairs. The value of each data character pair is formed by combining the values of the outside and
inside data characters. The data character pairs and their range of values are listed in Table 3.
Table 3 — Data character pair values
Outside data character Inside data character Data character pair
(n,k) values (V ) (n,k) values (V ) number of values value range
OUTSIDE INSIDE
(16,4) 2 841 (15,4) 1 597 4 537 077 0 to 4 537 076
The data character pair value V is calculated by:
PAIR
V = (1 597 × C ) + C
PAIR OUTSIDE INSIDE
where C and C are the data character values.
OUTSIDE INSIDE
To encode the pair value V into the outside and inside data characters C and C :
PAIR OUTSIDE INSIDE
C = V div V
OUTSIDE PAIR INSIDE
C = V mod V
INSIDE PAIR INSIDE
For example, if the data character pair value V is 1 971 265, then C and C are:
PAIR
OUTSIDE INSIDE
C = 1 971 265 div 1 597 = 1 234
OUTSIDE
C = 1 971 265 mod 1 597 = 567
INSIDE
The symbol value is calculated by combining the values of the left and right data character pair values. The
calculation is:
V = (4 537 077 × V ) + V
SYMBOL LPAIR RPAIR
where V is the symbol value and V and V are the left and right data character pair values.
SYMBOL LPAIR RPAIR
To encode the symbol value V into the left and right data character pairs V and V :
SYMBOL LPAIR RPAIR
V = V div 4 537 077
LPAIR SYMBOL
V = V mod 4 537 077
RPAIR SYMBOL
8 © ISO/IEC 2006 – All rights reserved

For example, if the symbol V is 1 234 567 890, Then the value of the left pair V and the value of the
SYMBOL
LPAIR
right pair V are:
RPAIR
V = 1 234 567 890 div 4 537 077 = 272
LPAIR
V = 1 234 567 890 mod 4 537 077 = 482 946
RPAIR
Combining the values of the data characters generates 20 585 067 703 929 values, however, only the first
20 000 000 000 000 values (0 to 19 999 999 999 999) are used. The high-order digit is the 2D component
linkage flag: 0 for a stand-alone RSS-14 and 1 if a 2D component adjoins the RSS-14 primary symbol. This
flag is stripped from the remaining 13 digits to form the item identification. An implied mod-10 check digit is
calculated and added to the end to form the EAN.UCC -14 identification number. A leading application
identifier prefix 01 is added to the transmitted data, immediately after the mandatory transmitted symbology
identifier, ]e0 or ]C1.
5.2.4 Finder patterns
The symbol has two finder patterns that also encode the symbol checksum. Each finder pattern can encode
nine values. The finder patterns are positioned between the first and second data characters and between the
fourth and third data characters. Since a finder pattern is adjacent to all four data characters, the symbol can
be scanned in four segments. Each segment will contain a data character and a finder pattern.
5.2.4.1 Finder pattern structure
The two finder patterns each consist of 5 elements comprising 15 modules. The left finder pattern starts and
ends with a space and the right finder pattern starts and ends with a bar. Finder pattern elements are
numbered from the outside to the inside of the symbol as shown in Figure 2.
The sum of the modules in the elements 2 and 3 is 10 to 12, while the sum of the modules in elements 4 and 5
is 2. The ratio of the wide element pair (2 and 3) to the total width of the four adjacent elements (2 through 5)
is in the range of 10:12 to 12:14. This ratio is used for the first step in the recognition logic for the finder
pattern. Table 4 lists the finder pattern element widths for the nine encoded values.
Table 4 — Finder pattern values and element widths
Element Widths (numbered from outside to inside)
Finder
Value
1 2 3 4 5
0 3 8 2 1 1
1 3 5 5 1 1
2 3 3 7 1 1
3 3 1 9 1 1
4 2 7 4 1 1
5 2 5 6 1 1
6 2 3 8 1 1
7 1 5 7 1 1
8 1 3 9 1 1
Finder pairs 8,0 and 0,8 are not used as 0 and 8 can be transformed into a reverse of the other with a single
1-X edge error. The remaining 79 possible pairs encode a mod 79 checksum value.
5.2.4.2 Checksum calculation
The two finder pattern values, C and C , each have nine possible values. Finder pattern value pairs 0,8
LEFT RIGHT
and 8,0 are not valid. This leaves a total of (9 × 9) - 2 or 79 combinations. The checksum value is equal to the
mod 79 residue of the weighted sum of the widths of the elements in the data characters.
© ISO/IEC 2006 – All rights reserved 9

The mod 79 checksum value is calculated by:
(W E + W E +…+ W E + W E +…+ W E ) mod 79
1,1 1,1 1,2 1,2 1,8 1,8 2,1 2,1 4,8 4,8
where W E is the product of the weight for data character N at ordinal element position M, from Table 5,
N,M N,M
and the module width of element M in data character N. The weights are successive powers of three mod 79.
Table 5 — Checksum calculation element weights
Data Character element ordinal positions
Data
Character
1 2 3 4 5 6 7 8
1 1 3 9 27 2 6 18 54
2 4 12 36 29 8 24 72 58
3 16 48 65 37 32 17 51 74
4 64 34 23 69 49 68 46 59
Encoding the two finder pattern values uses the following procedure:
temp = check value
if temp is greater than or equal to 8, then temp = temp + 1
if temp is greater than or equal to 72, then temp = temp + 1
C = temp div 9
LEFT
C = temp mod 9
RIGHT
See Annex F.1 for a complete example of checksum calculation and check character selection.
5.2.4.3 Decoding the finder pattern
The finder pattern is first identified by comparing the total width of four adjacent elements to the width of their
leftmost or rightmost pair of elements. For the finder pattern, the ratio is within the range of 12:9,5 to 14:12,5.
The left and right finder patterns are differentiated by their dark/light inversion.
The finder pattern and check for a valid data character to finder pattern pitch ratio should verify that a valid
RSS-14 symbol quarter segment has been scanned.
5.2.5 Reference decode algorithm
Bar code reading systems are designed to read imperfect symbols to the extent that practical algorithms
permit. This section describes the reference decode algorithm used in the computation of the decodability
value described in ISO/IEC 15416 for measuring symbol quality.
The algorithm contains the following steps to decode the symbol:
a) Find a segment by looking both left to right and right to left for a four-element sequence with the ratio:
for left to right:
9,5:12 ≤ ((element1 + element2): (element1 + element2 + element3 + element4)) ≤ 12,5:14

or for right to left:
9,5:12 ≤ ((element3 + element4): (element1 + element2 + element3 + element4)) ≤ 12,5:14

This ratio identifies the second through fifth elements of the finder.
10 © ISO/IEC 2006 – All rights reserved

Decode the finder pattern using the method in steps c) 1 to c) 3 to find the normalized edge-to-similar-
edge values E1 and E2 from the pitch, p, the sum of the first four element widths of the finder. Verify
that the values E1 and E2 correspond to a valid RSS-14 finder pattern.
b) Determine the direction and black-white inversion of the finder. Using the finder pattern and orientation,
determine which (n,k) pattern, (16,4) or (15,4), is appropriate for the adjacent data character along with its
leading element color, black or white.
c) For each adjacent data character with a (16,4) structure, decode it as follows:
1) Obtain the seven width measurements p, e , e , e , e , e , and e (Figure 3).
1 2 3 4 5 6
odd
odd odd odd
1 2 4
even
even even
even 3
2 4
e e
e
1 5
e e e
2 4 6
p
Figure 3 — Decode measurements
NOTE The diagram shows the first element as the left black element, but the data characters are also left-to-right
mirrored and/or dark-light inverted.
2) Convert measurements e , e , e , e , e , and e to normalized values E , E , E , E , E , and E which
1 2 3 4 5 6 1 2 3 4 5 6
will represent the integral module width (E ) of these measurements. The following method is used for
i
the i-th value.
If 1,5p/16 ≤ e < 2,5p/16, then E = 2
i i
If 2,5p/16 ≤ e < 3,5p/16, then E = 3
i i
If 3,5p/16 ≤ e < 4,5p/16, then E = 4
i i
If 4,5p/16 ≤ e < 5,5p/16, then E = 5
i i
If 5,5p/16 ≤ e < 6,5p/16, then E = 6
i i
If 6,5p/16 ≤ e < 7,5p/16, then E = 7
i i
If 7,5p/16 ≤ e < 8,5p/16, then E = 8
i i
If 8,5p/16 ≤ e < 9,5p/16, then E = 9
i i
Otherwise the character is in error.
3) Determine the normalized element widths from the E values. The last element is assigned the
remaining modules rather that being calculated from the E values. The set of valid element widths is
the only solution that has no element widths less than one module and has at least one even
element that is one module wide. For example the Figure 3 values E through E are {4 3 4 5 5 4 3}.
1 6
The possible derived element sets could be calculated as {4 0 3 1 4 1 3 0} (note the 0 width
elements), {3 1 2 2 3 2 2 1}, or {2 2 1 3 2 3 1 2} (note there are no single-module even-numbered
elements). Only the eight element widths {3 1 2 2 3 2 2 1} satisfy the requirements and therefore are
selected as the element widths. If no set of derived element widths is valid, then the character is in
error. Annex G gives a C-language implementation of this element width decoding algorithm.
© ISO/IEC 2006 – All rights reserved 11

4) Determine the values of the odd and even subsets from the program in Annex B.
5) Calculate the data character value from the odd and even subset values.
6) Calculate and store the weighted element widths for the checksum calculation.
d) For each adjacent data character with a (15,4) structure, decode it as follows:
1) Calculate the seven width measurements p, e , e , e , e , e , and e (as shown in Figure 3).
1 2 3 4 5 6
2) Convert measurements e , e , e , e , e , and e to normalized values E , E , E , E , E , and E which
1 2 3 4 5 6 1 2 3 4 5 6
will represent the integral module width (E ) of these measurements. The following method is used for
i
the i-th value.
If 1,5p/15 ≤ e < 2,5p/15, then E = 2
i i
If 2,5p/15 ≤ e < 3,5p/15, then E = 3
i i
If 3,5p/15 ≤ e < 4,5p/15, then E = 4
i i
If 4,5p/15 ≤ e < 5,5p/15, then E = 5
i i
If 5,5p/15 ≤ e < 6,5p/15, then E = 6
i i
If 6,5p/15 ≤ e < 7,5p/15, then E = 7
i i
If 7,5p/15 ≤ e < 8,5p/15, then E = 8
i i
If 8,5p/15 ≤ e < 9,5p/15, then E = 9
i i
Otherwise the character is in error.
3) Calculate the (15,4) data character value using the steps c) 1 through c) 3 above.
e) Decode the value of the finder pattern using the normalized element width method above and look up the
pattern in Table 4.
f) When all four data c
...