GS1 EPC Tag Data Standard 1.6 - Indicod-Ecr

478147824783478447854786478747884789479047914792479347944795479647974798479948004801480248034804480548064807480848094810481148124813481448154816481748184819I.9.1.2 Data/Directory and AuxMap indicator bitsA Data/Directory indicator bit is always encoded immediately following the last ID Map.By definition, a Data IDMPO has its Data/Directory bit set to ‘0’, and a DirectoryIDMPO has its Data/Directory bit set to ‘1’. If the Data/Directory bit is set to ‘1’, it isimmediately followed by an AuxMap indicator bit which, if ‘1’, indicates that an optionalAuxMap section immediately follows.I.9.1.3 Closing Flags bit(s)The ID Map section ends with a single Closing Flag: The final bit of the Closing Flags is an Addendum Flag Bit which, if ‘1’, indicatesthat there is an optional Addendum subsection encoded at the end of the Object Infosection of the Packed Object. If present, the Addendum subsection is as described inSection I .5.6.I.9.2 Directory Packed ObjectsA “Directory Packed Object” is an IDMPO whose Directory bit is set to ‘1’. Its onlyinherent difference from a Data IDMPO is that it does not contain any encoded dataitems. However, additional mechanisms and usage considerations apply only to aDirectory Packed Object, and these are described in the following subsections.I.9.2.1 ID Maps in a Directory IDMPOAlthough the structure of an ID Map is identical whether in a Data or Directory IDMPO,the semantics of the structure are somewhat different. In a Directory Packed Object’s IDMap bit field, each ‘1’ bit indicates that a Data Packed Object in the same data carriermemory bank contains a valid data item associated with the corresponding entry in thespecified Base Table for this ID Map. Optionally, a Directory Packed Object may furtherindicate which Packed Object contains each data item (see the description of the optionalAuxMap section below).Note that, in contrast to a Data IDMPO, there is no required correlation between the orderof bits in a Directory’s ID Map and the order in which these data items are subsequentlyencoded in memory within a sequence of Data Packed Objects.I.9.2.2 Optional AuxMap Section (Directory IDMPOs only)An AuxMap Section optionally allows a Directory IDMPO’s ID Map to indicate not onlypresence/absence of all the data items in this memory bank of the tag, but also whichPacked Object encodes each data item. If the AuxMap indicator bit is ‘1’, then anAuxMap section shall be encoded immediately after this bit. If encoded, the AuxMapsection shall contain one PO Index Field for each of the ID Maps that precede thissection. After the last PO Index Field, the AuxMap Section may optionally encode anObjectOffsets list, where each ObjectOffset generally indicates the number of bytes fromthe start of the previous Packed Object to the start of the next Packed Object. ThisAuxMap structure is shown (for an example IDMPO with two ID Maps) in Figure I 9-2.Figure I 9-2: Optional AuxMap section structureCopyright ©2005- 2011 GS1 AISBL, All Rights Reserved. Page 187 of 218