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Identifying Items

Apparel suppliers need to decide how they will assign unique serial numbers.
By Ken Traub
Jan 03, 2012Macy's Inc. recently announced that apparel suppliers to its Macy's and Bloomingdale's stores will be required to apply passive ultrahigh-frequency RFID tags to items that account for roughly 30 percent of the company's sales. Macy's joins Walmart and other retailers that are seeking huge gains in the efficiency and accuracy of in-store inventory management through RFID technology.

Apparel suppliers that will be RFID-tagging items at the point of manufacture need to understand "serialization"—the process of assigning a unique serial number to each item. That's true whether the supplier is RFID-tagging its own goods or delegating the tagging to a contract manufacturer or labeler.

Typically, the unique identifier is a Serialized Global Trade Item Number (SGTIN). The SGTIN includes the same GTIN product identifier already encoded into the Universal Product Code or European Article Number bar code, identical for all instances of the same product. The "S" is a unique serial number, and with 96-bit RFID tags, there can be 274 billion serial numbers for each GTIN.

There are four ways to choose the serial number for each tag. If a product is tagged only in one place, the supplier or its designated third party can assign serial numbers one at a time. Tagging software keeps a counter with each GTIN, and advances it as each tag is programmed.

When the same product is tagged on two or more lines, or by two or more third parties, the supplier must ensure the same number isn't used more than once. One method statically assigns large ranges to a tagging station or party—for example, it might reserve serial numbers 0 through 99,999,999,999 for plant "A," and 100,000,000,000 through 199,999,999,999 for plant "B." You don't need special software to make these allocations, but you must keep detailed records of them.

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