GS1 EPC Tag Data Standard 1.6 - Indicod-Ecr

4233423442354236423742384239I.5.1.3 IDMPO Object Info formatLeading Format Flags may define the Object Info structure to be an IDMPO, in which theLength Information (and optional Addendum subsection) follow an ID Map section (seeI.5.5). This arrangement ensures that the ID Map is in a fixed location for a givenapplication, of benefit when used as a Directory. The IDMPO Object Info structure isshown in Table I 5-3.Table I 5-3: IDMPO Object Info formatField Name: ID Map section Length Information AddendumUsage:One or more ID Mapstructures, each using adifferent ID TableThe number of octets inthis Object, plus a lastoctetpad indicatorOptionalpointer(s) toother ObjectscontainingEditinformationStructure: see I.9.1 See I.5.2 See I.5.642404241424242434244424542464247424842494250425142524253425442554256I.5.2 Length InformationThe format of the Length information, always present in the Object Info section of anyPacked Object, is shown in table I 5-4.Table I 5-4: Packed Object Length informationField Name: ObjectLength Pad IndicatorUsage:The number of 8-bit bytes in this ObjectThis includes the 1st byte of this PackedObject, including its IDLPO/IDMPOformat flags if present. It excludespatterns for use between packed objects,as specified in I.4.4If ‘1’: theObject’s last bytecontains at least1 padStructure: Variable: EBV-6 Fixed: 1 bitThe first field, ObjectLength, is an EBV-6 Extensible Bit Vector, consisting of one ormore repetitions of an Extension Bit and 5 value bits. An EBV-6 of ‘000100’ (value of4) indicates a four-byte Packed Object, An EBV-6 of ‘100001 000000’ (value of 32)indicates a 32-byte Object, and so on.The Pad Indicator bit immediately follows the end of the EBV-6 ObjectLength. This bitis set to ‘0’ if there are no padding bits in the last byte of the Packed Object. If set to ‘1’,then bitwise padding begins with the least-significant or rightmost ‘1’ bit of the last byte,and the padding consists of this rightmost ‘1’ bit, plus any ‘0’ bits to the right of that bit.This method effectively uses a single bit to indicate a three-bit quantity (i.e., the numberof trailing pad bits). When a receiving system wants to determine the total number of bits(rather than bytes) in a Packed Object, it would examine the ObjectLength field of thePacked Object (to determine the number of bytes) and multiply the result by eight, and (ifthe Pad Indicator bit is set) examine the last byte of the Packed Object and decrement theCopyright ©2005- 2011 GS1 AISBL, All Rights Reserved. Page 172 of 218