摘要 |
A method of generating a composition for identifying goods, the composition comprising an indicator material and a plurality of separately identifiable trace materials combined in such a manner to produce unique trace material combinations, the method comprising: defining a group of trace materials; selecting a plurality of trace materials from the group of trace materials to produce a unique combination; maintaining a record of the trace material combination; comparing further combinations of the trace materials to the record of trace material combinations; and either: if the further combination of trace materials is not found in the record, then generating a trace material combination based on the selected plurality of trace materials and recording the generated trace material combination in the record; or if the further combination of trace materials is found in the record of trace material combinations, re-selecting a different combination of trace materials and comparing this different combination to the record of trace material combinations and repeating until a unique combination of trace materials is selected which is not found in the record of trace material combinations, then generating a trace material combination based on the selected plurality of trace materials and recording the generated trace material combination in the record. |