GS1 EPC Tag Data Standard 1.6 - Indicod-Ecr

47404741474247434744474547464747474847494750475147524753475447554756475747584759476047614762476347644765476647674768476947704771477247734774477547764777477847794780I.5.3.1andI.5.3.2previous previous I.5.3.1 2 Flag BitWhen an ID Map section is encoded, it is always followed by an Object Length and PadIndicator, and optionally followed by an Addendum subsection (all as have beenpreviously defined), and then may be followed by any of the other sections defined forPacked Objects, except that a Directory IDMPO shall not include a Data section.I.9.1.1 ID Map and ID Map bit fieldAn ID Map usually consists of an Application Indicator followed by an ID Map bit field,ending with a Full/Restricted Use bit. An ID Map bit field consists of a single“MapPresent” flag bit, then (if MapPresent is ‘1’) a number of bits equal to the lengthdetermined from the ID Size pattern within the Application Indicator, plus one (theFull/Restricted Use bit). The ID Map bit field indicates the presence/absence of encodeddata items corresponding to entries in a specific registered Primary or Alternate BaseTable. The choice of base table is indicated by the encoded combination of DSFID andApplication Indicator pattern that precedes the ID Map bit field. The MSB of the ID Mapbit field corresponds to ID Value 0 in the base table, the next bit corresponds to ID Value1, and so on.In a Data Packed Object’s ID Map bit field, each ‘1’ bit indicates that this Packed Objectcontains an encoded occurrence of the data item corresponding to an entry in theregistered Base Table associated with this ID Map. Note that the valid encoded entrymay be found either in the first (“parentless”) Packed Object of the chain (the onecontaining the ID Map) or in an Addendum IDLPO of that chain. Note further that oneor more data entries may be encoded in an IDMPO, but marked “invalid” (by a Deleteentry in an Addendum IDLPO).An ID Map shall not correspond to a Secondary ID Table instead of a Base ID Table.Note that data items encoded in a “parentless” Data IDMPO shall appear in the samerelative order in which they are listed in the associated Base Table. However, additional“out of order” data items may be added to an existing data IDMPO by appending anAddendum IDLPO to the Object.An ID Map cannot indicate a specific number of instances (greater than one) of the sameID Value, and this would seemingly imply that only one data instance using a given IDValue can be encoded in a Data IDMPO. However, the ID Map method needs to supportthe case where more two or more encoded data items are from the same identifier “class”(and thus share the same ID Value). The following mechanisms address this need:Another data item of the same class can be encoded in an Addendum IDLPO of theIDMPO. Multiple occurrences of the same ID Value can appear on an ID List, eachassociated with different encoded values of the Secondary ID bits.A series of two or more encoded instances of the same “class” can be efficientlyindicated by a single instance of an ID Value (or equivalently by a single ID Map bit),if the corresponding Base Table entry defines a “Repeat” Bit (see J.2.2).An ID Map section may contain multiple ID Maps; a null Application Indicator section(with its AppIndicatorPresent bit set to ‘0’) terminates the list of ID Maps.Copyright ©2005- 2011 GS1 AISBL, All Rights Reserved. Page 186 of 218