Forensic Level Tags
Forensic level tags involve a complex authentication process and are often undetectable by normal methods. One example is DNA analysis, in which a strand binds with its complement and gives a machine-readable signal or a machine-readable hologram. When asked whether a person’s environment affects his body in an identifiable way, Jotcham noted that there is ongoing work on analyzing the bacteria that colonize the body and relating them to unique strains that may inhabit specific local environments.
Product Characteristic Tags
In-product analysis or authentication can be used to identify a specific product and determine if it has been diluted or subjected to other forms of tampering. The product itself can be characterized (by, for example, colorimetric testing, isotopic identification, spectroscopic fingerprinting, elemental analysis, and so on) or it can be identified by adding taggants such as molecules with hydrogen/deuterium isotope ratios (or ratios of other stable isotopes) that do not occur in nature. Commercial companies tend to be more interested in tracking the intermodal transportation of the aggregates through the supply chain rather than in tracking individual products per se.
Coding Tags
Coding (e.g., bar coding) provides a way for manufacturers to attach unique data or variable information to a product that creates a data stream as it moves through the supply chain. Bar coding had many skeptics when it was first proposed, but it is now inexpensive and ubiquitous and supported by a well-developed infrastructure. Unique identification data can be coded with an inkjet, and laser coding of identification data onto a product creates a tag that cannot easily be removed. Two-dimensional bar codes can be made very small (invisible to the eye) and may contain many times the information contained in one-dimensional bar codes.
Electronic Tags
Electronic tags can be used to identify a product’s current position to track its history of environmental changes and additions, and help to predict its future location and composition. Commercial industry primarily uses these tags to better control their supply chain dynamics and inventory. The best example is Dell Computer, which transformed the computer industry’s use of supply chain management to cut its operating costs and excess parts inventories. Jotcham discussed four levels of ID tags that can be used: the individual package (level 1); the display carton (level 2); the shipping case (level 3); and the pallet (level 4). With electronic tags, it is possible to read a level 1 code without opening the level 4 packaging. The best systems can alert the manufacturer when tampering has taken place. He pointed out that individuals can also be tracked by data generated in their everyday lives: drivers’ licenses, bill paying, insurance information, and payment of tolls and parking fees, as well as health care, schools, and work products.
Electronic tracking can be divided into chipless tags—for example, magnetic, electromagnetic, and antitheft electronic article surveillance (EAS) devices—and chip-containing tags, which may be passive, active, or smart active. In addition, there are electronic product codes (EPCs), which are tiny
