This invention is for a reader/writer device (terminal) for accessing item-related data in rewritable tags of the "RF-ID" type wherein each tag includes non-volatile memory. In a farm animal application each animal is implanted with an identified tag. From time to time, the terminal can be given a selected security level by reading password-like and individual identity data from a special tag held by an individual. As a result the individual can gain "read" and/or "write" to selected fields in the data record held within the tag. Further information may be added from time to time by empowered individuals. Schemes are enabled for the enhanced management of animals having such tags include accurate descriptors, proving ownership, showing compliance with disease control programmes and withholding periods after possible treatments, traceability of meat products from the shop to the farm, breeding schemes and performance recording. The use of security levels and the traceability of entries adds to the reliability of the stored information.