NOTE: this is a work-in-progress draft, please don't implement anything based on this yet. It's also missing a name. Suggestions very much appreciated.
UHF RFID tags (also known as "Gen 2" or "RAIN") are the lesser-known third type of RFID. Operating in the unlicensed 868MHz (EU)/900MHz (US) bands, they have a read range of up to 10m with a relatively low-cost, passive tag.
These tags are used by large retailers, including Decathlon and Uniqlo, for inventory control, barcodeless checkout, and theft prevention. (If you buy anything from Decathlon, make sure you cut the sewn-in tag out or your products will be uniquely trackable.)
UHF RFID tags include a unique identifier which usually either follows the GS1 Electronic Product Code standard or ISO/IEC 15961-1. Unfortunately, for both of these, you have to pay a hefty annual fee to get a prefix. To GS1's credit, all their specifications are freely available.