GS1 EPC Tag Data Standard 1.6 - Indicod-Ecr

17781779178017811782178317841785178617871788178917901791179217931794179517961797179817991800180118021803180418051806180718081809In the table above, attribute bits marked as “unassigned” are reserved for assignment byEPCglobal in future versions of this specification. Implementations of the encoding anddecoding rules specified herein SHALL accept any value of the attribute bits, whetherreserved or not. Applications, however, SHOULD direct an encoder to write a zero foreach unassigned bit, and SHOULD NOT rely upon the value of an unassigned bitdecoded from a tag, as doing so may cause interoperability problems if an unassignedvalue is assigned in a future revision to this specification.12 EPC Tag URI and EPC Raw URIThe EPC memory bank of a Gen 2 tag contains a binary-encoded EPC, along with othercontrol information. Applications do not normally process binary data directly. Anapplication wishing to read the EPC may receive the EPC as a Pure Identity EPC URI, asdefined in Section 6. In other situations, however, a capturing application may beinterested in the control information on the tag as well as the EPC. Also, an applicationthat writes the EPC memory bank needs to specify the values for control information thatare written along with the EPC. In both of these situations, the EPC Tag URI and EPCRaw URI may be used.The EPC Tag URI specifies both the EPC and the values of control information in theEPC memory bank. It also specifies which of several variant binary coding schemes is tobe used (e.g., the choice between SGTIN-96 and SGTIN-198). As such, an EPC TagURI completely and uniquely specifies the contents of the EPC memory bank. The EPCRaw URI also specifies the complete contents of the EPC memory bank, but repesentsthe memory contents as a single decimal or hexadecimal numeral.12.1Structure of the EPC Tag URI and EPC Raw URIThe EPC Tag URI begins with urn:epc:tag:, and is used when the EPC memorybank contains a valid EPC. EPC Tag URIs resemble Pure Identity EPC URIs, but withadded control information. The EPC Raw URI begins with urn:epc:raw:, and isused when the EPC memory bank does not contain a valid EPC. This includes situationswhere the toggle bit (bit 17 h ) is set to one, as well as situations where the toggle bit is setto zero but the remainder of the EPC bank does not conform to the coding rules specifiedin Section 14, either because the header bits are unassigned or the remainder of the binaryencoding violates a validity check for that header.The following figure illustrates these URI forms.Copyright ©2005- 2011 GS1 AISBL, All Rights Reserved. Page 66 of 218