GS1 EPC Tag Data Standard 1.6 - Indicod-Ecr

435243534354435543564357435843594360436143624363436443654366436743684369437043714372437343744375437643774378437943804381438243834384438543864387438843894390439143924393I.5.5 ID Values representation in an ID Map Packed ObjectEncoding an ID Map can be more efficient than encoding a list of ID Values, whenrepresenting a relatively large number of ID Values (constituting more than about 10percent of a large Base Table’s entries, or about 25 percent of a small Base Table’sentries). When encoded in an ID Map, each ID Value is represented by its relativeposition within the map (for example, the first ID Map bit represents ID Value “0”, thethird bit represents ID Value “2”, and the last bit represents ID Value ‘n’ (correspondingto the last entry of a Base Table with (n+1) entries). The value of each bit within an IDMap indicates whether the corresponding ID Value is present (if the bit is ‘1’) or absent(if ‘0’). An ID Map is always encoded as part of an ID Map Section structure (see I.9.1).I.5.6 Optional Addendum subsection of the Object Info sectionThe Packed Object Addendum feature supports basic editing operations, specifically theability to add, delete, or replace individual data items in a previously-written PackedObject, without a need to rewrite the entire Packed Object. A Packed Object that doesnot contain an Addendum subsection cannot be edited in this fashion, and must becompletely rewritten if changes are required.An Addendum subsection consists of a Reverse Links bit, followed by a Child bit,followed by either one or two EBV-6 links. Links from a Data Packed Object shall onlygo to other Data Packed Objects as addenda; links from a Directory Packed Object shallonly go to other Directory Packed Objects as addenda. The standard Packed Objectstructure rules apply, with some restrictions that are described in I.5.6.2.The Reverse Links bit shall be set identically in every Packed Object of the same “chain.”The Reverse Links bit is defined as follows: If the Reverse Links bit is ‘0’, then each child in this chain of Packed Objects is at ahigher memory location then its parent. The link to a Child is encoded as the numberof octets (plus one) that are in between the last octet of the current Packed Object andthe first octet of the Child. The link to the parent is encoded as the number of octets(plus one) that are in between the first octet of the parent Packed Object and the firstoctet of the current Packed Object. If the Reverse Links bit is ‘1’, then each child in this chain of Packed Objects is at alower memory location then its parent. The link to a Child is encoded as the numberof octets (plus one) that are in between the first octet of the current Packed Object andthe first octet of the Child. The link to the parent is encoded as the number of octets(plus one) that are in between the last octet of the current Packed Object and the firstoctet of the parent.The Child bit is defined as follows: If the Child bit is a ‘0’, then this Packed Object is an editable “Parentless” PackedObject (i.e., the first of a chain), and in this case the Child bit is immediately followedby a single EBV-6 link to the first “child” Packed Object that contains editingaddenda for the parent. If the Child bit is a ‘1’, then this Packed Object is an editable “child” of an edited“parent,” and the bit is immediately followed by one EBV-6 link to the “parent” and aCopyright ©2005- 2011 GS1 AISBL, All Rights Reserved. Page 176 of 218