The invention relates to a system comprising: a self-contained unit (2) including a first (11) data carrier having an electronic identification device that is readable by radio frequency and the reading of which activates an electronic data sheet in a first (3) database; and a third (13) data carrier including a second identification code readable by an optical reader (6). The invention also relates to a method which uses the reading of the third (13) data carrier to activate an electronic data sheet in a second (4) database, and to allow the associative data between both identification codes to be visualised.