AS NZS ISO 28560.2:2015 pdf download – Information and documentation – RFID in libraries
6.2 Primary item identifier
The primary item identifier is a mandatory data element defined in ISO 28560-1. This is the only mandatory data element that is required to be encoded to be compliant with this part of ISO 28560. The format is variable length, and the alphanumeric characters can be any from ISO/IEC 646 International Reference Version (also known as US-ASCII). Although the encoding rules support any length of primary item identifier, shorter codes and all-numeric codes encode more efficiently, requiring less memory and enabling faster transactions across the air interface. Although locking the primary item identifier is optional, under normal circumstances, this data element should be locked to prevent various forms of digital vandalism. The primary item identifier shall be encoded as the first data element on the RFID tag to allow for faster transactions across the air interface by invoking a Read-First-Object(s) argument in the read command (see B.5).
6.3 Content parameter
The content parameter is an optional data element used to declare the Relative-OID values that are encoded on the RFID tag, and for the purposes of this part of ISO 28560 is used as an OID index. It should be used if additional data elements are encoded on the RFID tag. If used, it can be an aid to faster reading, because it indicates the presence or absence of a particular data element. If the desired data element is encoded on the tag, then additional reading is required, whereas if the OID index indicates that it is not on the tag, the wasted transaction time can be eliminated. The index, itself, consists of a bit sequence, where each bit position is associated with a particular Relative-OID. If the bit position is set“1″, then the Relative-OID and associated data object is encoded on the RFID tag. As Relative-OID 1 is mandatory and Relative-OID 2 is this particular data element, the bit map begins at Relative-OID 3. An example is shown in Figure 2.
In the example in Figure 2, the OID index indicates that Relative-OID values 3, 8, and 11 are encoded. Irrespective of whether the data dictionary includes other Relative-OID values, the bit map can be truncated at this last Relative-OID that is encoded. It is also necessary to round up the bit map to 8-bit boundaries for encoding on the RFID tag. If this data element is encoded on the RFID tag, it should be in the second position so that the data capture system can be set up to read the primary item identifier and the OID index in a single read process. The OID index should only be locked if the information on the RFID tag is certain to remain unchanged. This data element provides no information about the sequence of the encoded data elements, nor their size. In the example in Figure 2, the encoding sequence could be Relative-OID value 8 followed by 11, followed by 3.