ISO IEC 24723 pdf download – Information technology — Automatic identification and data capture techniques — GS1 Composite bar code symbology specification
The date is encoded by stripping the two-digit Al 11 or Al 17 from the date element string and encoding theremaining six digits into 16 bits using the equation above.For Al 11, the next bit is “0″ ; for Al 17 the next bit is“1″. lf there was no date, a 2-bit field of “11” is encoded instead of the 17-bit field.
lf a lot number directly follows the date element string, the two-digit Al 10 is stripped from the lot numberelement string, and the remainder of the lot number element string is encoded using general-purpose datacompaction，directly following the date field. lf more Al element strings follow the lot number， a FNC1separates the lot number data from the next Al element string to be encoded.
lf a lot number does not directly follow the date element string, a FNC1 is encoded following the date elementstring, even if no more data follows the date element string (this FNC1 shall not be transmitted by thedecoder). If more data follows, it is encoded using general-purpose data compaction beginning with the digitsof the next AI.
The decoder shall reconstruct the Al element strings from a compressed data field using an EncodationMethod field of “10”according to the following procedure:
a) lf the bits “11” follow the method “10”, no date is encoded, and the decoder shall insert the two-digit Al 10before the remaining general-purpose data compaction field is decoded.
b) Otherwise, the 6-digit date shall be extracted according to the above equation. lf the seventeenth bit is “o”,
an Al 11 for production date is added as a prefix by the decoder. If the seventeenth bit is “1”, an Al 17 forexpiration date is added. If the first encoded data character following the date field is FNC1, there is no lotnumber (this FNC1 shall not be transmitted by the decoder). Otherwise the decoder shall insert the two-digit Al 10 before the remaining general-purpose data compaction field is decoded.
5.3.2 Encodation Method field of“11”— Al 90
This Encodation Method may be used if an element string with an Al 90 occurs at the start of the datamessage，and if the data field following the two-digit Al 9o starts with an alphanumeric substring whichcomplies with a specific format. The format of the alphanumeric data that can be used in this compactionmethod is 0,1,2, or 3 digits (strings with leading zeros do not comply with the required format) followed by anuppercase alphabetic character.
An Encodation Method field of “11″ is followed by a compressed data field which includes the encodedspecial-format alphanumeric string，followed by the remainder of its data field,optionally additionalcompressed data fields, and optionally additional Al element strings.
The compressed data field following the “11”Encodation Method consists of the following:
a) One or two bits indicating the starting data encodation scheme used for the remainder of the Al 90 data
field.A “”0” indicates Alphanumeric encodation, a “10” indicates Numeric encodation and an”11″ indicatesAlpha encodation (see’5.3.3).
b) One or two bits indicating the absence or presence，respectively，of specific Als after the first FNC1
(which terminates the Al 90 element string, unless no further data is encoded). “0” indicates that either nomore data is encoded,or that the remaining data is encoded according to general-purpose datacompaction rules. Otherwise, the Al of the next element string will not be explicitly encoded.”10” indicatesthat an Al 21 follows, and “11” indicates that an Al 8004 follows.
c)Nine or 20 bits encoding the 1 to 4 characters of the alphanumeric string that followed the Al 90 in the
source message, encoded as follows:
1) Convert the numeric portion of the alphanumeric string to a value. If the string contains no numeric
digits, the value is 0.
ISO IEC 24723 pdf download – Information technology — Automatic identification and data capture techniques — GS1 Composite bar code symbology specification
