1、DRAFT FOR DEVELOPMENT DD ENV 12925:1998 Bar coding Symbology specifications “PDF417” ICS 35.040DDENV12925:1998 This Draft for Development, having been prepared under thedirection of the DISC Board,was published under theauthority of the Standards Board and comes into effect on 15February1998 BSI 10-
2、1999 ISBN 0 580 29188 X National foreword This Draft for Development is the English language version of ENV12925:1997. This publication is not to be regarded as a British Standard. It is being issued in the Draft for Development series of publications and is of a provisional nature because the subje
3、ct matter is still under development requiring wider exposure. It should be applied on this provisional basis, so that information and experience of its practical application may be obtained. Comments arising from the use of this Draft for Development are requested so that UK experience can be repor
4、ted to the European organization responsible for its conversion into a European Standard. A review of this publication will be initiated2 years after its publication by the European organization so that a decision can be taken on its status at the end of its three-year life. The commencement of the
5、review period will be notified by an announcement in Update Standards. According to the replies received by the end of the review period, the responsible BSI Committee will decide whether to support the conversion into a European Standard, to extend the life of the prestandard or to withdraw it. Com
6、ments should be sent in writing to the Secretary of BSI Technical Committee IST/34, Bar coding, at389 Chiswick High Road, London, W44AL, giving the document reference and clause number and proposing, where possible, an appropriate revision of the text. A list of organizations represented on this com
7、mittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by
8、using the “Find” facility of the BSI Standards Electronic Catalogue. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theENV title page, pages2 to90 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorpo
9、rated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsDDENV12925:1998 BSI 10-1999 i Contents Page National foreword Inside front cover Foreword 2 Text of ENV 12925 5ii blankEUROPEAN PRESTANDARD PRNORME EUROPENNE EURO
10、PISCHE VORNORM ENV 12925 December 1997 ICS 35.040 Descriptors: Data processing, character recognition, optical recognition, bar codes, symbols, specifications English version Bar coding Symbology Specifications “PDF417” This European Prestandard (ENV) was approved by CEN on17November1997 as a prospe
11、ctive standard for provisional application. The period of validity of this ENV is limited initially to three years. After two years the members of CEN will be requested to submit their comments, particularly on the question whether the ENV can be converted into a European Standard. CEN members are r
12、equired to announce the existence of this ENV in the same way as for an EN and to make the ENV available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the ENV) until the final decision about the possible conversio
13、n of the ENV into an EN is reached. CEN members are the national standards bodies of Austria, Belgium, CzechRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee f
14、or Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1997 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. ENV 12925:1997 EENV12925:1997 BSI 10-1999 2
15、 Foreword This European Prestandard has been prepared by Technical Committee CEN/TC225 “Bar coding”, the secretariat of which is held by NNI. Organisations contributing to the development of the standard include: Symbol Technologies Inc (as original inventors of “PDF417” symbology) AIM Europe (Autom
16、atic Identification Manufacturers) AIM USA (Automatic Identification Manufacturers) According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to announce this European Prestandard: Austria, Belgium, CzechRepublic, Denmark, Finland, F
17、rance, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Contents Page Foreword 2 Introduction 5 1 Scope 5 2 Normative References 5 3 Definitions, Mathematical Symbols and Abbreviations 5 3.1 Definitions 5 3.2 Math
18、ematical Symbols and Operations 7 3.3 Abbreviations 8 4 Requirements 8 4.1 Symbology Characteristics 8 4.1.1 Basic Characteristics 8 4.1.2 Summary of Additional Features 8 4.2 Symbol Structure 9 4.2.1 “PDF417” Symbol Parameters 9 4.2.2 Row Parameters 10 4.2.3 Codeword Sequence 10 4.3 Basic Encodatio
19、n 11 4.3.1 Symbol Character Structure 11 4.3.2 Start and Stop Characters 11 4.4 High Level (Data) Encodation 12 4.4.1 Function Codewords 12 4.4.2 Text Compaction Mode 14 4.4.3 Byte Compaction Mode 18 4.4.4 Numeric Compaction Mode 19 4.4.5 Advice to Select the Appropriate Compaction Mode 21 4.4.6 Tre
20、atment of “PDF417” Reserved Codewords 21 4.5 Extended Channel Interpretation 21 4.5.1 Encoding the ECI Assignment Number 22 4.5.2 Pre-assigned Extended Channel Interpretations 22 4.5.3 Encoding ECI Sequences Within Compaction Modes 23 4.5.4 Post-Decode Protocol 24 4.6 Determining the Codeword Sequen
21、ce 25 4.7 Error Detection and Correction 25 4.7.1 Error Correction Level 25 4.7.2 Error Correction Capacity 25 4.7.3 Defining the Error Correction Codewords 26 4.8 Dimensions 26 4.9 Defining the Symbol Format 27ENV12925:1997 BSI 10-1999 3 Page 4.9.1 Defining the Aspect Ratio of the Module 27 4.9.2 D
22、efining the Symbol Matrix of Rows and Columns 27 4.10 Generating the Error Correction Codewords 28 4.11 Low Level Encodation 29 4.11.1 Clusters 30 4.11.2 Determining the Symbol Matrix 30 4.11.3 Determining the Values of the Left and Right Row Indicators 30 4.11.4 Row Encoding 31 4.12 Compact “PDF417
23、” 31 4.13 Macro “PDF417” 31 4.13.1 Compaction Modes and Macro “PDF417” 31 4.13.2 ECIs and Macro “PDF417” 31 4.14 User Guidelines 32 4.14.1 Human Readable Interpretation 32 4.14.2 Autodiscrimination Capability 32 4.14.3 User-defined Application Parameters 32 4.14.4 “PDF417” Symbol Quality 32 4.15 Ref
24、erence Decode Algorithm 32 4.16 Error Detection and Error Correction Procedure 33 4.17 Transmitted Data 33 4.17.1 Transmitted Data in the Basic (Default) Interpretation 33 4.17.2 Transmission Protocol for Extended Channel Interpretation (ECI) 33 4.17.3 Transmitted Data For Macro “PDF417” 34 4.17.4 T
25、ransmission of Reserved Codewords Using the ECI Protocol 34 4.17.5 Symbology Identifier 34 4.17.6 Transmission Using Older Protocols 34 Annex A (normative) Encoding/Decoding Table of “PDF417” Symbol Character X-Sequences 35 Annex B (normative) The Default Character Set for Byte Compaction Mode 58 An
26、nex C (normative) Base256 to Base900 Conversion Algorithm 59 Annex D (normative) Base10 to Base900 Conversion Algorithm 60 Annex E (normative) User Selection of Error Correction 61 E.1 Recommended Error Correction Level 61 Page E.2 Other User Consideration of the Error Correction Level 61 Annex F (n
27、ormative) Tables of Coefficients for Calculating “PDF417” Error Correction Codewords 62 Annex G (normative) Compact “PDF417” 65 Annex H (normative) Macro “PDF417” 66 H.1 Macro “PDF417” Overview 66 H.2 Macro “PDF417” Syntax 66 H.2.1 The Segment Index 67 H.2.2 File ID Field 67 H.2.3 Optional Fields 68
28、 H.2.4 Macro “PDF417” Terminator 69 H.3 High Level Encoding Considerations 69 H.4 Encodation Example 69 H.5 Macro “PDF417” and Extended Channel Interpretation 70 H.5.1 Macro “PDF417” with ECI000000 and000001 (GLI0 and1) 70 H.5.2 Macro “PDF417” and Other ECIs 70 H.6 Macro “PDF417” Data Transmission 7
29、0 H.6.1 Operating in Buffered Mode 71 H.6.2 Operating in Unbuffered Mode 71 H.6.3 Reset-to-Zero Transmissions 72 Annex J (normative) Testing “PDF417” Symbol Quality 72 J.1 Grade Based on Start and Stop Characters 72 J.2 Grade Based on Symbol Characters 72 J.3 Overall Symbol Grade 73 Annex K (normati
30、ve) Reference Decode Algorithm for “PDF417” 73 K.1 Initialisation 73 K.2 Reference Decode Algorithm for Line Decoding 73 K.3 Filling the Matrix 75 K.4 Interpretation 75 Annex L (normative) Error Correction Procedures 76 Annex M (normative) Symbology Identifier 77 Annex N (normative) Transmission Pro
31、tocol for Decoders Conforming to Earlier “PDF417” Standards 78 N.1 Basic Channel Encodation 78 N.2 GLI Encoded Symbols 78 N.3 Macro “PDF417” Symbols 79 N.3.1 Transmission in Buffered Mode 79ENV12925:1997 BSI 10-1999 4 Page N.3.2 Transmission in Unbuffered Mode 79 N.4 Transmission of Reserved Codewor
32、ds Using the Original “PDF417” Protocol 80 N.5 Achieving Compatibility Between Old and New “PDF417” Equipment 80 N.5.1 Encoders 80 N.5.2 Decoders 81 Annex P (informative) Algorithm to Minimise the Number of Codewords 82 Annex Q (informative) Autodiscrimination Compatibility 83 Annex R (informative)
33、Guidelines to Determine the Symbol Matrix 83 Annex S (informative) Calculating the Coefficients for Generating the Error Correction Codewords Worked Example 86 Annex T (informative) Generating the Error Correction Codewords Worked Example 87 Annex U (informative) Division Circuit Procedure for Gener
34、ating Error Correction Codewords 89 Annex V (informative) Bibliography 90 Figure 1 “PDF417” Symbol Structure 9 Figure 2 “PDF417” Example of Symbol Layout Schematic 10 Figure 3 A “PDF417” Symbol Character 11 Figure 4 “PDF417” Start and Stop Characters 12 Figure 5 Available Mode Switching 14 Figure 6
35、Text Compaction Sub-Mode Switching 17 Figure 7 Valid Locations for ECI Escape Sequences in Byte Compaction Mode 24 Figure 8 Typical “PDF417” Symbol Schematic Showing the Positioning of Codewords 30 Figure G.1 Compact “PDF417” 66 Figure H.1 “PDF417” Symbol Layouts 67 Figure K.1 Decode Measurements 74
36、 Figure K.3 Schematic Showing a Scan Line Crossing Rows 75 Figure L.1 Symbol Syndrome Divider 76 Figure U.1 Error Correction Codeword Encoding Circuit 89 Table 1 X-Sequence for Start and Stop Characters 12 Table 2 Assignments of “PDF417” Function Codewords 13 Page Table 3 Mode Definition and Mode Sw
37、itching Codewords 13 Table 4 Mode Transition Table, Showing Codewords and Their Function 13 Table 5 Text Compaction Sub-Mode Definition 15 Table 6 Example of Text Compaction Encoding 16 Table 7 Text Compaction Sub-Mode Transition Table 17 Table 8 Encoding ECI Assignment Numbers 22 Table 9 Error Corr
38、ection Levels and Error Correction Codewords 25 Table 10 Possible Error Correction Combinations for Error Correction Level3 26 Table E.1 Recommended Error Correction Level 61 Table H.1 Macro “PDF417” Optional Field Designators 68 Table J.1 Symbol Grade in Relation to Unused Error Correction 73 Table
39、 M.1 Symbology Identifier Option Values for “PDF417” 77ENV12925:1997 BSI 10-1999 5 Introduction The technology of bar coding is based on the recognition of patterns encoded in bars and spaces of defined dimensions. There are various methods of encoding information in bar code form, known as symbolog
40、ies, and the rules defining the translation of characters into bar and space patterns and other essential features are known as the symbology specification. Symbologies are of two broad categories: A traditional simple format of linear symbologies, where data is encoded as a single string from left
41、to right. A more sophisticated format of two-dimensional symbologies where data is encoded in an arrangement of rows and columns. “PDF417” is a two-dimensional symbology. Manufacturers of bar code equipment and users of bar code technology require publicly available standard symbology specifications
42、 to which they can refer when developing equipment and application standards. It is the intent and understanding of CEN that the symbology presented in this standard is entirely in the public domain and free of all user restrictions, licences and fees. 1 Scope This European Standard specifies the re
43、quirements for the bar code symbology known as “PDF417”. It specifies “PDF417” symbology characteristics, data character encodation, symbol formats, dimensions, tolerances, error correction rules, decoding algorithm, and a number of application parameters. 2 Normative References This standard incorp
44、orates by dated or undated reference provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed below. For dated references, subsequent amendments to or revisions of any of these publications apply to this standard o
45、nly when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN796, Bar Coding Symbology Identifiers. EN 841, Bar Coding Symbology Specifications Format Description. prEN 1556, Bar Coding Terminology. prEN 1635, Bar Coding Te
46、st Specifications for Bar Code Symbols. ISO/IEC 646:1991, Information Processing ISO7-bit Coded Character Set for Information Exchange: International Reference Version. NOTEThe code table is equivalent to ANSI X3.4-1986. ISO 8859-1, Information Processing 8-bit Single-byte Coded Graphic Character Se
47、ts Part1: Latin Alphabet No. 1. Extended Channel Interpretation Assignment Standard published by AIM International 3 Definitions, Mathematical Symbols and Abbreviations 3.1 Definitions For the purposes of this standard the following definitions in prEN1556 shall apply. algorithm, application standar
48、d, ASCII, autodiscrimination, bar, bar code, bi-directional, binary, bit, codeword, column, continuous code, data character, data codeword, data compaction, data region, decode algorithm, decoder, element, encode, error correction level, human readable character, leading zeros, linear symbology, mod
49、ule, modulo, multi-row symbology, n,k symbology, numeric, overhead, pad character, pad codeword, quiet zone, reference decode algorithm, row, scanner, self-checking, space, start character, stop character, symbol aspect ratio, symbol character, symbology, symbology identifier, symbol width, X dimension, Y dimension The following definitions also apply to this standard. 3.1.1 Basic Channel Model a standard system for encoding and transmitting bar code data where only data message b
