ISO/IEC 21471:2020

INTERNATIONAL ISO/IEC
STANDARD 21471
First edition
2020-02
Information technology — Automatic
identification and data capture
techniques — Extended rectangular
data matrix (DMRE) bar code
symbology specification
Technologies de l'information – Techniques de l'identification et de
saisie de données automatiques – Data Matrix Rectangulaire Etendu
(DMRE) spécification de symbologie de code à barres
Reference number
ISO/IEC 21471:2020(E)
©
ISO/IEC 2020

---------------------- Page: 1 ----------------------
ISO/IEC 21471:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/IEC 21471:2020(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms and mathematical/logical notations.1
3.1 Terms and definitions . 1
3.2 Symbols and abbreviated terms. 2
3.3 Mathematical/logical notations . 2
4 Symbol description . 2
4.1 Basic characteristics . 2
4.2 Summary of additional features . 3
4.3 Symbol structure . 3
4.3.1 General. 3
4.3.2 Finder pattern . 4
4.3.3 Symbol sizes and capacities . 4
5 DMRE code requirements . 4
5.1 Encoding procedure overview. 4
5.2 Data encodation . 5
5.2.1 Overview . 5
5.2.2 Default character interpretation . 5
5.2.3 ASCII encodation . 5
5.2.4 Symbology control characters . 6
5.2.5 C40 encodation. 8
5.2.6 Text encodation . 9
5.2.7 ANSI X12 encodation. 9
5.2.8 EDIFACT encodation .10
5.2.9 Base 256 encodation .11
5.3 User considerations .12
5.3.1 General.12
5.3.2 User selection of extended channel interpretation .12
5.3.3 User selection of symbol size and shape .12
5.4 Extended channel interpretation .12
5.4.1 General.12
5.4.2 Encoding ECIs .12
5.4.3 ECIs and Structured append .13
5.4.4 Post-decode protocol .13
5.5 DMRE code symbol attributes .13
5.5.1 Symbol sizes and capacity .13
5.5.2 Insertion of alignment patterns into larger symbols .14
5.6 Structured append .14
5.6.1 Basic principles .14
5.6.2 Symbol sequence indicator .14
5.6.3 File identification .15
5.6.4 FNC1 and Structured append .15
5.6.5 Buffered and unbuffered operation .15
5.7 Error detection and correction .16
5.7.1 Reed-Solomon error correction .16
5.7.2 Generating the error correction codewords .16
5.7.3 Error correction capacity .17
5.8 Symbol construction .17
5.8.1 General.17
5.8.2 Symbol character placement .17
© ISO/IEC 2020 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO/IEC 21471:2020(E)

5.8.3 Alignment pattern module placement .18
5.8.4 Finder pattern module placement .18
6 Symbol dimensions .18
6.1 Dimensions .18
7 Symbol quality .18
7.1 General .18
7.2 Symbol quality parameters .19
7.2.1 Fixed pattern damage .19
7.2.2 Scan grade and overall symbol grade.19
7.2.3 Grid non-uniformity .19
7.2.4 Decode .19
7.3 Process control measurements.19
8 Reference decode algorithm for DMRE .19
9 User guidelines .29
9.1 Human readable interpretation .29
9.2 Autodiscrimination capability .29
9.3 System considerations .29
10 Transmitted data .29
10.1 General .29
10.2 Protocol for FNC1 .29
10.3 Protocol for FNC1 in the second position .30
10.4 Protocol for Macro characters in the first position .30
10.5 Protocol for ECIs .30
10.6 Symbology identifier .30
10.7 Transmitted data example .31
Annex A (informative) Code pattern .32
Annex B (normative) Rectangular data matrix code encodation character sets .34
Annex C (informative) Rectangular data matrix code alignment patterns .38
Annex D (normative) Reed-Solomon error detection and correction .39
Annex E (informative) Symbol character placement .43
Annex F (normative) DMRE print quality – Symbology-specific aspects .51
Annex G (normative) Symbology identifier .60
Annex H (informative) Encode example .61
Annex I (informative) Encoding data using the minimum symbol data characters for
extended rectangular data matrix code .64
Annex J (informative) Useful process control techniques .68
Annex K (informative) Autodiscrimination capability .70
Annex L (informative) System considerations .71
Bibliography .72
iv © ISO/IEC 2020 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/IEC 21471:2020(E)

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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for
the different types of document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents) or the IEC
list of patent declarations received (see http:// patents .iec .ch).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 31, Automatic identification and data capture techniques.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO/IEC 2020 – All rights reserved v

---------------------- Page: 5 ----------------------
ISO/IEC 21471:2020(E)

Introduction
Extended rectangular data matrix (DMRE) is a two-dimensional matrix symbology which is made up
of nominally square modules arranged within a perimeter finder pattern. Though primarily shown and
described in this document as a dark symbol on light background, rectangular data matrix symbols can
also be printed to appear as light on dark.
This document is an extension of ISO/IEC 16022, to which it adds rectangular formats. Maximum
compatibility is a design goal. In consequence, most clauses of ISO/IEC 16022 are identical to those of
this document, including the module placement algorithm and the reference decode algorithm.
This document is published separately because existing equipment supporting ISO/IEC 16022 will not
recognize DMRE symbols. Only equipment that is enabled and configured to support DMRE will be
capable of printing and scanning the new rectangular formats. To avoid user confusion due to this fact,
a separate and complete document was developed.
Manufacturers of bar code equipment and users of the technology require publicly available standard
symbology specifications to which they can refer when developing equipment and application
standards. The publication of standardized symbology specifications is designed to achieve this.
vi © ISO/IEC 2020 – All rights reserved

---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO/IEC 21471:2020(E)
Information technology — Automatic identification and
data capture techniques — Extended rectangular data
matrix (DMRE) bar code symbology specification
1 Scope
This document defines the requirements for the symbology known as extended rectangular data matrix
(DMRE). It specifies the DMRE code symbology characteristics, data character encodation, symbol
formats, dimensions and print quality requirements, error correction rules, decoding algorithm, and
user-selectable application parameters.
It applies to all DMRE code symbols produced by any printing or marking technology.
Original data matrix code sizes are not covered by this document but defined in ISO/IEC 16022 using
the same matrix placement, decoding and error correction algorithm.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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/IEC 8859-1, Information technology — 8-bit single-byte coded graphic character sets — Part 1: Latin
alphabet No. 1
ISO/IEC 15415, Information technology — Automatic identification and data capture techniques — Bar
code symbol print quality test specification — Two-dimensional symbols
ISO/IEC 19762, Information technology — Automatic identification and data capture (AIDC) techniques —
Harmonized vocabulary
1)
ISO/IEC 29158:— , Information technology — Automatic identification and data capture techniques —
Direct Part Mark (DPM) Quality Guideline
3 Terms, definitions, symbols and abbreviated terms and mathematical/logical
notations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 19762 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
1) Under preparation. Stage at the time of publication: ISO/IEC/DIS 29158:2020.
© ISO/IEC 2020 – All rights reserved 1

---------------------- Page: 7 ----------------------
ISO/IEC 21471:2020(E)

3.1.1
codeword
symbol character value
intermediate level of coding between source data and the graphical encodation in the symbol
3.1.2
module
single cell in a matrix symbology used to encode one bit of data
Note 1 to entry: In DMRE, the module is nominally a square shape.
3.1.3
pattern randomising
procedure which converts an original bit pattern to another bit pattern by inverting selected bits
Note 1 to entry: The resulting bitstream is less likely to have repeating patterns.
3.2 Symbols and abbreviated terms
d number of error correction codewords
e number of erasures
N the numerical base in an encodation scheme
p number of codewords reserved for error detection
S symbol character
t number of errors
X horizontal and vertical width of a module
ε error correction codeword
DMRE extended rectangular data matrix
ECI extended channel interpretation
DPM direct part marking
3.3 Mathematical/logical notations
div integer division operator
mod integer remainder after division
XOR exclusive or logic function whose output is one only when its two inputs are not equivalent
LSB least significant bit
MSB most significant bit
4 Symbol description
4.1 Basic characteristics
DMRE is a two-dimensional matrix symbology.
2 © ISO/IEC 2020 – All rights reserved

---------------------- Page: 8 ----------------------
ISO/IEC 21471:2020(E)

The characteristics of DMRE are:
a) Encodable character set:
1) values 0 to 127 in accordance with ISO/IEC 646, i.e. all 128 ASCII characters (equivalent to the
U.S. national version of ISO 646);
2) values 128 to 255 in accordance with ISO 8859-1. These are referred to as extended ASCII.
b) Representation of data: a dark module is a binary one and a light module is a zero.
This document specifies DMRE symbols in terms of dark modules marked on a light background.
However, 4.2 provides that symbols may also be produced with the module’s colours reversed. In
such symbols, dark modules would be a binary zero, and light modules would be a binary 1.
c) Symbol size in modules (not including quiet zone): 8 × 48 to 26 × 64 even values only (see Table 7).
Symbol sizes 8 × 18, 8 × 32, 12 × 26, 12 × 36, 16 × 36 and 16 × 48 are defined by ISO/IEC 16022 and
are not covered by this document. These rectangular data matrix sizes are fully compatible with
this document.
d) Data characters per symbol (for maximum symbol size):
1) alphanumeric data: up to 175 characters;
2) 8-bit byte data: 116 characters;
3) numeric data: 236 digits.
e) Code type: rectangular matrix.
f) Orientation independence: yes.
g) Error detection and correction: ECC 200 Reed Solomon. No support for ECC 000 to ECC 140.
4.2 Summary of additional features
The following summarizes additional features which are inherent or optional in DMRE:
a) Reflectance reversal (inherent): symbols are intended to be read when marked so that the image is
either dark on light or light on dark (see Figure 1). The specifications in this document are based on
dark images on a light background, therefore references to dark or light modules should be taken as
references to light or dark modules respectively in the case of symbols produced with reflectance
reversal.
b) Extended channel interpretations (ECI) (optional): this mechanism enables characters from other
character sets (e.g. Arabic, Cyrillic, Greek, Hebrew) and other data interpretations or industry-
specific requirements to be represented.
c) Structured append (optional): this allows files of data to be represented in up to 16 rectangular
data matrix symbols. The original data can be correctly reconstructed regardless of the order in
which the symbols are scanned.
4.3 Symbol structure
4.3.1 General
Each DMRE symbol consists of data regions which contain nominally square modules set out in a
regular array. In larger symbols, data regions are separated by alignment patterns (as illustrated in
Figures C.1 and C.2). The data region is surrounded by a finder pattern, and this shall be surrounded
© ISO/IEC 2020 – All rights reserved 3

---------------------- Page: 9 ----------------------
ISO/IEC 21471:2020(E)

on all four sides by a quiet zone border. Figure 1 illustrates two representations of a rectangular data
matrix symbol.
a) DMRE, dark on light b) DMRE, light on dark
Figure 1 — DMRE "A1B2C3D4E5F6G7H8I9J0K1L2"
4.3.2 Finder pattern
The finder pattern is a perimeter to the data region and is one module wide. Two adjacent sides, the left
and lower sides, forming the L boundary, are solid dark lines; these are used primarily to determine
physical size, orientation and symbol distortion. The two opposite sides are made up of alternating
dark and light modules. These are used primarily to define the cell structure of the symbol, but also
can assist in determining physical size and distortion. The extent of the quiet zone is indicated by the
corner marks in Figure 1.
4.3.3 Symbol sizes and capacities
DMRE code symbols have an even number of rows and an even number of columns. The symbols are
rectangular with sizes from 8 × 48 to 26 × 64 not including quiet zones. For all rectangular data matrix
code symbols the upper right corner module is light in the dark on light version (see Figure 1). The
complete attributes are given in Table 7.
5 DMRE code requirements
5.1 Encoding procedure overview
This subclause provides an overview of the encoding procedure. The following subclauses provide
more details. An encoding example for DMRE code is given in Annex H. The following steps convert user
data to a DMRE code symbol:
Step 1: Data encodation
As DMRE code includes various encodation schemes that allows a defined set of characters to be
converted into codewords more efficiently than the default scheme, analyse the data stream to identify
...