Abstract: Unauthorized removal of articles e.g. from a retail store, each article carrying a read/write tag, is detected by a security system having at least one point-of-sale apparatus (30) arranged to write specific data into (or erase specific data from) the tag to indicate that the article has been paid for, and a detector apparatus (40) for the or each exit of the store and arranged to read each tag to determine if the specific data has been written into (or erased from) the tag, and otherwise to initiate an alarm. The system also includes a refunds/returns detector apparatus (50) to read the tag of each article presented to it, to determine if the specific data has been written into (or erased from) the tag, and to erase (or write in) that data so that the article can be returned to stock.

Abstract: Unauthorized removal of articles e.g. from a retail store, each article carrying a read/write tag, is detected by a security system having at least one point-of-sale apparatus (30) arranged to write specific data into (or erase specific data from) the tag to indicate that the article has been paid for, and a detector apparatus (40) for the or each exit of the store and arranged to read each tag to determine if the specific data has been written into (or erased from) the tag, and otherwise to initiate an alarm. The system also includes a refunds/returns detector apparatus (50) to read the tag of each article presented to it, to determine if the specific data has been written into (or erased from) the tag, and to erase (or write in) that data so that the article can be returned to stock.