RFC 1884: “IP Model six Addressing Architecture” uses that phrase for a few bits at the end of an IPv6 deal with. (The quantity of bits looked as if it would differ in some distinct examples, but this identifier was ordinarily dependant on the MAC-48 handle of the network card.) https://lead-generation-service-n41739.onesmablog.com/5-tips-about-whatsmyipv6-you-can-use-today-66253716