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Public Review - DotCode Second Public Review Document
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Notice of Public Review

* Public Review Ends September 1, 2017 *

AIM announces the second Public Review Draft of the International Symbology Standard - DotCode developed by the AIM Technical Symbology (TSC) Committee.

DotCode is a public domain optical data carrier designed to be reliably readable when printed by high-speed inkjet or laser dot technologies.  With this standard, real time data like expiration date, lot number or serial number can be applied to products in a machine-readable form at production line speeds.


This AIM, Inc. document has been revised after a first public review that was held on July 6, 2017.*


If you wish to review or provide comments, please follow these steps:

NOTE: Public review documents are DRAFTS and no commercial decisions should be made based on their content. Anyone intending to use information from this document for implementation purposes must wait for the final published document which will be made available in the AIM Store as soon as it is finalized. 


* REVISION SUMMARY: This document has been revised from Rev. 2.00 to Rev. 4.0.  [This 2nd Public Review Document is enumerated DRAFT 0.09.]  In addition to several minor changes, such as correcting typographical errors and clarifying ambiguous text, substantive changes have also been made.  However, there is no change that would affect or obsolete a reader that was designed according to the earlier version of the specification.


Most importantly, “ANNEX A, Dot Pattern Scoring Routine (Normative)” has been updated to detect extremely rare but hard-to-decode symbol patterns and give them a lower score as part of the mask-selection process.  The new scoring algorithm may result in the selection of a different mask (and therefore a different dot pattern) from the previous method.  However, this encoding algorithm change imposes no new requirements for existing symbol decoders and DotCode symbols created in conformance with earlier versions of this standard using the original ANNEX A algorithm remain completely valid. 

Further, where the time it takes to perform the complete 4-mask evaluation presents a problem for very high-speed applications where encoding calculation time is critical, this revision of the DotCode symbology specification permits the mask-selection process to be abbreviated to improve the speed of encoding, while still maintaining robust symbol integrity.  See Section 5.2.4.

Also of note, section “12  Symbol print quality” has been expanded to define additional symbology-specific assessment of certain graded parameters specified by ISO/IEC 15415.  These are Grid non-uniformity and Axial non-uniformity.  The additional symbology-specific quality parameter “Print” growth has been renamed Average Normalized Dot Size and the grading scale for this parameter has been clarified. 

The DotCode special characters previously named Bin Shift A (codeword 110) and Bin Shift B (codeword 111) have been renamed to Upper Shift A and Upper Shift B, respectively (see Table 1), in order to clearly distinguish them from similarly named code characters with different meanings in other symbologies.  References to these characters in various Annexes to this specification have been updated.  The reference to Bin Latch (codeword 112) in Table 1 has been changed to Binary Latch.  Other references to Binary Latch are unchanged.

Other minor changes amplify a note given in “Table 2 – Code Set B dual-function codewords” with reference to Codeword 100 concerning the value of “xx”; and correct a pair of typographical errors in in the “arbitrary message” example given at the beginning of section “6.2 Encoding an application-specific 96-bit data packet”, where the value “4816” should have been given as “3016” (representing an encoded value of “0”) and the value “4916” should have been given as “3116” (representing an encoded value of “1”).

Note about DotCode Rev. 3.0: Rev. 3.0 was posted online in error for a brief time in 2014 but then withdrawn.  Rev. 3.0 as published contained numerous format and other errors and is not valid.  Any copies should be deleted or destroyed.

Rev. 2.00 was an update to Rev. 1.36 to correct a small number of subtle but potentially serious errors in the encoding examples in section 5.2.4; and in the encoding algorithm source code in Annex A.  Rev. 2.00 differs from Rev. 1.36 only with respect to these encoding changes.  There is no change that would affect or obsolete a reader that was designed according to the earlier version of the specification.

In exactly five (5) places in section 5.2.4 an incorrect Pad character codeword was given.  This occurred in the paragraph beginning “The four masking options” and also in the last codeword of each of the four masking examples.  The correct values are shown in bold type so the reader may easily discern them.  In exactly four (4) places in the C language source code in “Annex A – Dot pattern scoring routine (normative)”, the variable “last” was not initialized.  The added code (“last=”) is shown in bold type. 

Separate from this document, AIM, Inc. also provides the C language source code file “DotEncod.c” - DotCode (rev 2.00) Encoding Module.  Versions prior to rev 2.00 failed to initialize the variable “last” (as described above with respect to the source code in Annex A).  This has been corrected in exactly four (4) places, which can be found by searching for "REV 2.00 FIX" in the “DotEncod.c” source code listing.  A fifth change to this source code corrects an error in the computation of the number of Pad characters to be added.  The corrected line, which can also be found by searching for "REV 2.00 FIX", reads: 
“if (ND > nd) AddPads(cw,nd,ND-nd); // REV 2.00 FIX”.

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2/27/2018 » 3/1/2018

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