ISO/IEC 15438:2015

INTERNATIONAL ISO/IEC
STANDARD 15438
Third edition
2015-09-15
Information technology — Automatic
identification and data capture
techniques — PDF417 bar code
symbology specification
Technologies de l’information — Techniques automatiques
d’identification et de capture des données — Spécifications pour la
symbologie de code à barres PDF417
Reference number
©
ISO/IEC 2015
© ISO/IEC 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO/IEC 2015 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols, operations and abbreviated terms . 3
4.1 Symbols . 3
4.2 Mathematical operations . 4
4.3 Abbreviated terms . 4
5 Requirements . 4
5.1 Symbology characteristics . 4
5.1.1 Basic characteristics . 4
5.1.2 Summary of additional features . 5
5.2 Symbol structure . 6
5.2.1 PDF417 symbol parameters . 6
5.2.2 Row parameters . 6
5.2.3 Codeword sequence . 7
5.3 Basic encodation . 8
5.3.1 Symbol character structure . 8
5.3.2 Start and stop characters . 9
5.4 High level (data) encodation . 9
5.4.1 Function codewords .10
5.4.2 Text Compaction mode .12
5.4.3 Byte Compaction mode .17
5.4.4 Numeric Compaction mode .19
5.4.5 Advice to select the appropriate compaction mode .20
5.4.6 Treatment of PDF417 reserved codewords.20
5.5 Extended Channel Interpretation .21
5.5.1 Encoding the ECI assignment number .22
5.5.2 Pre-assigned and default Extended Channel Interpretations .22
5.5.3 Encoding ECI sequences within compaction modes .23
5.5.4 Post-decode protocol .25
5.6 Determining the codeword sequence .25
5.7 Error detection and correction .25
5.7.1 Error correction level .25
5.7.2 Error correction capacity .26
5.7.3 Defining the error correction codewords.26
5.8 Dimensions .27
5.8.1 Minimum width of a module (X) .27
5.8.2 Row height (Y) .27
5.8.3 Quiet zones .27
5.9 Defining the symbol format .27
5.9.1 Defining the aspect ratio of the module .27
5.9.2 Defining the symbol matrix of rows and columns .28
5.10 Generating the error correction codewords .29
5.11 Low level encodation .30
5.11.1 Clusters .31
5.11.2 Determining the symbol matrix .31
5.11.3 Determining the values of the left and right row indicators .32
5.11.4 Row encoding .32
5.12 Compact PDF417 .32
5.13 Macro PDF417 .32
© ISO/IEC 2015 – All rights reserved iii

5.13.1 Compaction modes and Macro PDF417 .33
5.13.2 ECIs and Macro PDF417 .33
5.14 User guidelines .33
5.14.1 Human readable interpretation .33
5.14.2 Autodiscrimination capability .33
5.14.3 User-defined application parameters .33
5.14.4 PDF417 symbol quality .34
5.15 Reference decode algorithm.34
5.16 Error detection and error correction procedure .34
5.17 Transmitted data .34
5.17.1 Transmitted data in the basic (default) interpretation .34
5.17.2 Transmission protocol for Extended Channel Interpretation (ECI) .35
5.17.3 Transmitted data for Macro PDF417 .36
5.17.4 Transmission of reserved codewords using the ECI protocol .36
5.17.5 Symbology identifier .36
5.17.6 Transmission using older protocols .36
Annex A (normative) Encoding/decoding table of PDF417 symbol character bar-
space sequences .37
Annex B (normative) The default character set for Byte Compaction mode .60
Annex C (normative) Byte Compaction mode encoding algorithm .61
Annex D (normative) Numeric Compaction mode encoding algorithm .63
Annex E (normative) User selection of error correction level .65
Annex F (normative) Tables of coefficients for calculating PDF417 error correction codewords .66
Annex G (normative) Compact PDF417 .70
Annex H (normative) Macro PDF417 .71
Annex I (normative) Testing PDF417 symbol quality .79
Annex J (normative) Reference decode algorithm for PDF417 .80
Annex K (normative) Error correction procedures .84
Annex L (normative) Symbology identifier .86
Annex M (normative) Transmission protocol for decoders conforming with original
PDF417 standards .87
Annex N (informative) Algorithm to minimise the number of codewords .93
Annex O (informative) Guidelines to determine the symbol matrix .95
Annex P (informative) Calculating the coefficients for generating the error correction
codewords – worked example .99
Annex Q (informative) Generating the error correction codewords - worked example .100
Annex R (informative) Division circuit procedure for generating error correction codewords .104
Annex S (informative) Additional guidelines for the use of PDF417 .106
Bibliography .108
iv © ISO/IEC 2015 – 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.
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).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/IEC JTC 1, Information technology, Subcommittee
SC 31, Automatic identification and data capture techniques.
This third edition cancels and replaces the second edition (ISO/IEC 15438:2006), of which it constitutes
a minor revision.
© ISO/IEC 2015 – All rights reserved v

Introduction
The technology of bar coding is based on the recognition of patterns of bars and spaces of defined
dimensions. There are various methods of encoding information in bar code form, known as
symbologies, and the rules defining the translation of characters into bars and space patterns and other
essential features are known as the symbology specification.
Manufacturers of bar code equipment and users of bar code technology require publicly available
standard symbology specifications to which they can refer when developing equipment and application
standards. It is the intent and understanding of ISO/IEC that the symbology presented in this
International Standard is entirely in the public domain and free of all user restrictions, licences and fees.
vi © ISO/IEC 2015 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 15438:2015(E)
Information technology — Automatic identification and
data capture techniques — PDF417 bar code symbology
specification
1 Scope
This International Standard specifies the requirements for the bar code symbology known as PDF417.
It specifies PDF417 symbology characteristics, data character encodation, symbol formats, dimensions,
error correction rules, reference decoding algorithm, and a number of application parameters.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. 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 15415, Information technology — Automatic identification and data capture techniques — Bar
code symbol print quality test specification — Two-dimensional symbols
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 — GS1
Composite bar code symbology specification
3 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
basic channel model
standard system for encoding and transmitting bar code data where data message bytes are output
from the decoder but no control information about the message is transmitted
Note 1 to entry: A decoder complying with this model operates in Basic Channel Mode.
3.2
bar-space sequence
sequence which represents the module widths of the elements of a symbol character
© ISO/IEC 2015 – All rights reserved 1

3.3
cluster
any of the three mutually exclusive subsets of PDF417 symbol characters
Note 1 to entry: The symbol characters in a given cluster conform with particular structural rules which are
used in decoding the symbology.
3.4
compaction mode
any of the three data compaction algorithms in PDF417 (Text, Numeric and Byte Compaction modes)
which are used to map 8-bit data bytes efficiently to PDF417 codewords
3.5
e-distance
distance from the leading edge of an element to the leading edge of the next similar element, or from
trailing edge to trailing edge
3.6
error correction codeword
encodes a value derived from the error correction codeword algorithm to enable decode errors to be
detected and, depending on the error correction level, to be corrected
3.7
Extended Channel Interpretation
ECI
procedure within some symbologies, including PDF417, to replace the default interpretation with
another interpretation in a reliable manner
Note 1 to entry: The interpretation intended prior to producing the symbol can be retrieved after decoding the
scanned symbol to recreate the data message in its original format.
3.8
Extended Channel Model
system for encoding and transmitting both data message bytes and control information about the
message, the control information being communicated using Extended Channel Interpretation (ECI)
escape sequences
Note 1 to entry: A decoder complying with this model operates in Extended Channel Mode.
3.9
function codeword
initiates a particular operation within a symbology
EXAMPLE To switch between data encoding sets, to invoke a compaction scheme, to program the reader, or
to invoke Extended Channel Interpretations.
3.10
Global Label Identifier
GLI
procedure in the PDF417 symbology which behaves in a similar manner to Extended Channel
Interpretation
Note 1 to entry: The GLI system was the PDF417-specific precursor to the symbology-independent ECI system.
3.11
Macro PDF417
procedure in the PDF417 symbology logically to distribute data from a computer file across a number of
related PDF417 symbols
Note 1 to entry: The procedure considerably extends the data capacity beyond that of a single symbol.
Note 2 to entry: This procedure is similar to the Structured Append feature in other symbologies.
2 © ISO/IEC 2015 – All rights reserved

3.12
Mode Latch codeword
used to switch from one mode to another mode, which stays in effect until another latch or shift
codeword is implicitly or explicitly brought into use, or until the end of the symbol is reached
3.13
Mode Shift codeword
used to switch from one mode to another for one codeword, after which encoding returns to the
original mode
3.14
Row Indicator codeword
PDF417 codeword adjacent to the start or stop character in a row, which encodes information about the
structure of the PDF417 symbol in terms of the row identification, total number of rows and columns,
and the error correction level
3.15
Symbol Length Descriptor
first codeword in a PDF417 symbol, which encodes the total number of data codewords in the symbol
4 Symbols, operations and abbreviated terms
4.1 Symbols
For the purposes of this International Standard, the following mathematical symbols apply. There are
some cases where the symbols below have been used in a different manner in an equation. This has been
done for consistency with a more general use of the notation and is always clearly defined in the text.
A symbol aspect ratio (height to width) of a PDF417 symbol
b element width in a symbol character
c number of columns in the symbol in the data region (excluding start, stop and row indicator code-
words)
d data codeword including all function codewords
E error correction codeword
e edge to similar edge dimension in a symbol character
F row number
f number of substitution errors
H height of symbol including quiet zone
K cluster number
k number of error correction codewords
L left row indicator
l number of erasures
m number of source data codewords prior to the addition of the Symbol Length Descriptor and any
pad codewords
n total number of data codewords including Symbol Length Descriptor and any pad codewords
© ISO/IEC 2015 – All rights reserved 3

p pitch or width of a symbol character
Q horizontal quiet zone
H
Q vertical quiet zone
V
R right row indicator
r number of rows in the symbol
s error correction level
W width of symbol including quiet zone
X X-dimension or module width
Y module height (also called row height)
4.2 Mathematical operations
For the purposes of this International Standard, the following mathematical operations apply.
div is the integer division operator, rounding down
INT is the integer value, i.e. where a number is rounded down to its whole number component,
ignoring its decimal fractions
mod is the positive integer remainder after division. If the remainder is negative, add the value of the
divisor to make it positive. For example, the remainder of –29 160 divided by 929 is –361 which
when added to 929 yields 568.
4.3 Abbreviated terms
For the purposes of this International Standard, the following abbreviated terms apply.
ECI Extended Channel Interpretation
GLI Global Label Identifier
5 Requirements
5.1 Symbology characteristics
5.1.1 Basic characteristics
PDF417 is a bar code symbology with the following basic characteristics.
a) Encodable character set:
1) Text Compaction mode (see 5.4.1.5) permits all printable ASCII characters to be encoded,
i.e. values 32 to 126 inclusive in accordance with ISO/IEC 646 (IRV), as well as selected
control characters;
2) Byte Compaction mode (see 5.4.3) permits all 256 possible 8-bit byte values to be encoded.
This includes all ASCII characters value 0 to 127 inclusive and provides for international
character set support;
3) Numeric Compaction mode (see 5.4.4) permits efficient encoding of numeric data strings;
4 © ISO/IEC 2015 – All rights reserved

4) Up to 811 800 different character sets or data interpretations;
5) Various function codewords for control purposes.
b) Symbol character structure: (n, k, m) characters of 17 modules (n), 4 bar and 4 space elements (k),
with the largest element 6 modules wide (m).
c) Maximum possible number of data characters per symbol (at error correction level 0): 925 data
codewords which can encode:
1) Text Compaction mode: 1 850 characters (at 2 data characters per codeword);
2) Byte Compaction mode: 1 108 characters (at 1,2 data characters per codeword);
3) Numeric Compaction mode: 2 710 characters (at 2,93 data characters per codeword).
At the minimum recommended error correction level, there is a maximum of 863 data codewords
which can encode:
4) Text Compaction mode: 1 726 characters (at 2 data characters per codeword);
5) Byte Compaction mode: 1 033 characters (at 1,2 data characters per codeword);
6) Numeric Compaction mode: 2 528 characters (at 2,93 data characters per codeword).
d) Symbol size:
1) Number of rows: 3 to 90;
2) Number of columns: 1 to 30;
3) Width in modules: 90X to 583X including quiet zones;
4) Maximum codeword capacity: 928 codewords;
5) Maximum data codeword capacity: 925 codewords.
Since the number of rows and the number of columns are selectable, the aspect ratio of a PDF417
symbol may be varied when printing to suit the spatial requirements of the application.
e) Selectable error correction: 2 to 512 codewords per symbol (see 5.7).
f) Non-data overhead:
1) Per row: 73 modules, including quiet zones;
2) Per symbol: a minimum of 3 codewords, represented as symbol characters.
g) Code type: continuous, multi-row two-dimensional.
h) Character self-checking: Yes.
i) Bi-directionally decodable: Yes.
5.1.2 Summary of additional features
Additional features which are inherent or optional in PDF417 are summarised below.
a) Data compaction: (inherent) Three schemes are defined to compact a number of data characters
into codewords. Generally data is not directly represented on a one character for one codeword
basis (see 5.4.1.5 to 5.4.4).
b) Extended Channel Interpretations: (optional) These mechanisms allow up to 811 800 different
data character sets or interpretations to be encoded (see 5.5).
© ISO/IEC 2015 – All rights reserved 5

c) Macro PDF417: (optional) This mechanism allows files of data to be represented logically and
consecutively in a number of PDF417 symbols. Up to 99 999 different PDF417 symbols can be
so linked or concatenated and be scanned in any sequence to enable the original data file to be
correctly reconstructed (see 5.13).
d) Edge to edge decodable: (inherent) PDF417 can be decoded by measuring elements from edge to
similar edge (see 5.3.1).
e) Cross row scanning: (inherent) The combination of the following three characteristics in PDF417
facilitates cross row scanning:
1) being synchronised horizontally, or self clocking;
2) row identification;
3) being synchronised vertically, by using the cluster values to achieve local row discrimination.
This combination allows a single linear scan to cross a number of rows and achieve a partial decode
of the data so long as at least one complete symbol character per row is decoded into its codeword.
The decoding algorithm can then place the individual codewords into a meaningful matrix.
f) Error correction: (inherent) A user may define one of 9 error correction levels. All but Level 0 not
only detect errors but also can correct erroneously decoded or missing codewords (see 5.7).
g) Compact PDF417: (optional) In relatively ‘clean’ environments, it is possible to reduce some of the
row overhead to improve the symbol density (see 5.12).
NOTE In earlier specifications of PDF417, Compact PDF417 was called Truncated PDF417. Compact PDF417 is
the preferred term to avoid confusion with the more general use of the term ‘truncated’.
5.2 Symbol structure
5.2.1 PDF417 symbol parameters
Each PDF417 symbol consists of a stack of vertically aligned rows with a minimum of 3 rows (maximum
90 rows). Each row shall include a minimum of 1 symbol character (maximum 30 symbol characters),
excluding start, stop and row indicator columns. The symbol shall include a quiet zone on all four sides.
Figure 1 illustrates a PDF417 symbol encoding the text: PDF417 Symbology Standard.
Figure 1 — PDF417 symbol structure
5.2.2 Row parameters
Each PDF417 row shall comprise of the following:
a) leading quiet zone;
6 © ISO/IEC 2015 – All rights reserved

b) start character;
c) left row indicator symbol character;
d) 1 to 30 symbol characters;
e) right row indicator symbol character;
f) stop character;
g) trailing quiet zone.
NOTE The number of symbol characters (or codewords) defined in item ‘d’ above is equal to the number of
data columns in the PDF417 symbol.
5.2.3 Codeword sequence
A PDF417 symbol may contain up to 928 symbol characters or codewords. Symbol character is the
more appropriate term to refer to the printed bar/space pattern; codeword is more appropriate for the
numeric value of the symbol character. The codewords shall follow this sequence:
a) The first codeword, the Symbol Length Descriptor, shall always encode the total number of data
codewords in the symbol, including the Symbol Length Descriptor itself, data codewords and pad
codewords, but excluding the number of error correction codewords.
b) The data codewords shall follow, from the most significant encodable character. Function
codewords may be inserted to achieve data compaction.
c) Pad codewords to enable the codeword sequence to be represented in a rectangular matrix. Pad
codewords may also be used to fill additional complete rows to achieve an aspect ratio desired or
as specified by the application.
d) An optional Macro PDF417 Control Block.
e) Error correction codewords for error detection and correction.
The codewords are arranged with the most significant codeword adjacent to the Symbol Length
Descriptor, and are encoded from left to right and from top row to bottom. Figure 2 illustrates in layout
format the sequence for a symbol like what is being shown in Figure 1. In Figure 2, an error correction
level of 1 has been used and one pad character was needed to completely fill the symbol matrix.
L d d R
1 15 14 1
L d d R
2 13 12 2
L d d R
3 11 10 3
S
L d d R
4 9 8 4
S
T
L d d R
5 7 6 5 T
A
L d d R O
6 5 4 6
R
P
L d d R
7 3 2 7
T
L d d R
8 1 0 8
L E E R
9 3 2 9
L E E R
10 1 0 10
Figure 2 — PDF417 Example of Symbol Layout Schematic
© ISO/IEC 2015 – All rights reserved 7

where
L, R, d and E are as defined in Clause 4;
d Symbol Length Descriptor (in this example, with a value of 16);
d to d encoded representation of data;
14 1
d pad codeword.
The rules and advice for structuring the matrix are included in 5.9.
5.3 Basic encodation
5.3.1 Symbol character structure
Each PDF417 symbol character shall consist of four bar elements and four space elements, each of which
can be one to six modules wide. The four bar and four space elements shall measure 17 modules in total.
PDF417 symbol characters can be decoded by measuring the e-distances within the character.
Each symbol character is defined by an 8-digit bar-space sequence which represents the module widths
of the eight elements of that symbol character. Figure 3 illustrates a symbol character with the bar-
space sequence 51111125.
Figure 3 — A PDF417 symbol character
There are 929 defined symbol character values (codewords) numbered from 0 to 928.
The codewords are represented by three mutually exclusive symbol character sets, or clusters. Each
cluster encodes the 929 available PDF417 codewords into different bar-space patterns so that one
cluster is distinct from another. The cluster numbers are 0, 3, and 6. The cluster definition applies to all
PDF417 symbol characters, except for start and stop characters.
The cluster number K is defined by the following formula:
K = (b - b + b - b +) mod 99
1 2 3 4
where b , b , b and b represent the width in modules of the four bar elements respectively.
1 2 3 4
8 © ISO/IEC 2015 – All rights reserved

The cluster number K for the symbol character in Figure 3 is:
K = (5 - 1 + 1 - 2 + 9) mod 9 = 3
The codewords and the bar-space sequences for each cluster of symbol characters are given in Annex A.
5.3.2 Start and stop characters
The start and stop characters shall be composed as defined in Table 1 and illustrated in Figure 4:
Table 1 — Bar-space sequence for Start and Stop Characters
Bar-space sequence
Character
B S B S B S B S B
Start 8 1 1 1 1 1 1 3
Stop 7 1 1 3 1 1 1 2 1
NOTE 1 The PDF417 stop and start characters are unique in having elements more than 6 modules wide.
NOTE 2 The stop character has one extra single module bar element.
The start and stop characters shall have the same bar-space sequence for all rows.
Figure 4 — PDF417 Start and Stop Characters
5.4 High level (data) encodation
High level encoding converts the data characters into their corresponding codewords.
Data compaction schemes shall be used to achieve efficient high level encoding. Three modes are
defined below, each of which defines a particular efficient mapping between user defined data and
codeword sequences. PDF417 has three data compaction modes:
— Text Compaction mode (see 5.4.1.5);
— Byte Compaction mode (see 5.4.3);
— Numeric Compaction mode (see 5.4.4).
A given string of data bytes may be represented by different codeword sequences, depending on how
the encoder switches between compaction modes and sub-modes. There is no single specified way to
encode data in a PDF417 symbol.
900 codewords (0 to 899) are available in each mode for data encodation and other functions within
the mode. The remaining 29 codewords are assigned to specific functions (see 5.4.1) independent of the
current compaction mode.
© ISO/IEC 2015 – All rights reserved 9

PDF417 also supports the Extended Channel Interpretation system, which allows different
interpretations of data to be accurately encoded in the symbol (see 5.5).
5.4.1 Function codewords
Codewords 900 to 928 are assigned as function codewords as follows:
— for switching between modes (see 5.4.1.1);
— for enhanced applications using Extended Channel Interpretations (ECIs) (see 5.4.1.2);
— for other enhanced applications (see 5.4.1.3 and 5.4.1.4).
At present codewords 903 to 912, 914 to 917, and 919 are reserved. Table 2 defines the complete list of
assigned and reserved function codewords. Their functions are defined in 5.4.1.1 to 5.4.1.5. See 5.4.6 for
the treatment of reserved codewords.
Table 2 — Assignments of PDF417 function codewords
Codeword Function Refer to subclause
900 mode latch to Text Compaction mode 5.4.1.1
901 mode latch to Byte Compaction mode 5.4.1.1, 5.4.3.1
902 mode latch to Numeric Compaction mode 5.4.1.1
903 to 912 Reserved
913 mode shift to Byte Compaction mode 5.4.1.1
914 to 917, 919 Reserved
918 linkage flag to associated linear component, in a composite symbol 5.4.1.5
(other than an EAN.UCC Composite symbol)
920 linkage flag to associated linear component, in an EAN.UCC Compos- 5.4.1.5
ite symbol
921 reader initialisation 5.4.1.4
922 terminator codeword for Macro PDF control block 5.13
923 sequence tag to identify the beginning of optional fields in the Macro 5.13
PDF control block
924 mode latch to Byte Compaction mode (used differently from 901) 5.4.1.1, 5.4.3.1
925 to 927 identifier for an Extended Channel Interpretation (ECI) 5.5
928 Macro marker codeword to indicate the beginning of a Macro PDF 5.13
Control Block
5.4.1.1 Function codewords for mode switching
In one PDF417 symbol it is possible to switch back and forth between modes as often as required.
Advice about selecting the appropriate modes is given in 5.4.5.
A Mode Latch codeword may be used to switch from the current mode to the indicated destination
mode which stays in effect until another mode switch is explicitly brought into use. Codewords 900 to
902 and 924 are assigned for this purpose. Table 3 defines their function.
The Mode Shift codeword 913 shall cause a temporary switch from Text Compaction mode to Byte
Compaction mode. This switch shall be in effect for only the next codeword, after which the mode shall
revert to the prevailing sub-mode of the Text Compaction mode. Codeword 913 is only available in Text
Compaction mode; its use is described in 5.4.2.4.
10 © ISO/IEC 2015 – All rights reserved

Table 3 — Mode Definition and Mode Switching Codewords
Destination Mode Mode Latch Mode Shift
Text Compaction 900
Byte Compaction 901/924 913
Numeric Compaction 902
NOTE The table identifies the codeword to be used to switch to the defined mode.
The switching rules between the three modes are defined in Table 4 and shown schematically in Figure 5.
Table 4 — Mode Transition Table, Showing Codewords and Their Function
Destination Mode
Original Mode
Text Byte Numeric
Text 900 mode latch 913 mode shift 902 mode latch
901 mode latch
924 mode latch
Byte 900 mode latch 901 mode latch 902 mode latch
924 mode latch
Numeric 900 mode latch 901 mode latch 902 mode latch
924 mode latch
Key
mode shift
mode latch
Figure 5 — Available Mode Switching
The switching rules into Byte Compaction mode are more fully defined in 5.4.3.1.
© ISO/IEC 2015 – All rights reserved 11

5.4.1.2 Function codewords for switching to Extended Channel Interpretations
An ECI codeword can be used to switch to a particular interpretation, which stays in effect until
another ECI codeword is explicitly brought into use or until the end of the data. Codewords 925 to 927
are assigned to this function (see 5.5).
5.4.1.3 Function codewords for Macro PDF417
Macro PDF417 symbols (see 5.13) shall use codeword 928 at the start of the Macro PDF417 Control
Block. Codewords 922 and 923 are used for special functions in Macro PDF417.
5.4.1.4 Function codeword for reader initialisation
Codeword 921 shall be used to instruct the reader to interpret the data contained within the symbol
as programming for reader initialisation. Codeword 921 shall appear as the first codeword after the
Symbol Length Descriptor. In the case of a Macro PDF417 initialisation sequence, codeword 921 shall
appear in every symbol.
The data contained in an initialisation symbol or sequence of symbols shall not be transmitted by the
reader.
5.4.1.5 Function codewords for linkage flags in composite symbols
Codeword 920 shall be used as a linkage flag to signal the presence of an associated EAN.UCC linear
component in accordance with ISO/IEC 24723.
Codeword 918 shall be used as a linkage flag to signal the presence of an associated linear component
in any other composite symbology.
When used, the 918 or 920 codeword may appear in any position in the symbol. The applicable
composite symbology specification may define a specific position of the linkage flag.
Readers supporting the indicated composite application should decode and transmit the data from all
components as specified in the relevant composite symbology specification. Readers not supporting
the indicated composite application may treat the 918 or 920 codeword as a reserved codeword (see
5.4.6). In addition, readers not supporting the indicated 918 composite application may have an option
to ignore the two-dimensional composite component and transmit only the data from the associated
linear component.
5.4.2 Text Compaction mode
The Text Compaction mode includes all the printable ASCII characters (i.e. values from 32 to 126)
and three ASCII control characters: HT or tab (ASCII value 9), LF or line feed (ASCII value 10), and CR
or carriage return (ASCII value 13). The Text Compaction mode also includes various latch and shift
characters which are used exclusively within the mode.
The Text Compaction mode encodes up to 2 characters per codeword. The compaction rules for converting
data into PDF417 codewords are defined in 5.4.2.2. The sub-mode switches are defined in 5.4.2.3.
5.4.2.1 Text Compaction sub-modes
The Text Compaction mode has
...