IVI Translation refers to a stateless IPv4/IPv6 translation technique.
[1] It allows hosts in different address families (IPv4 and IPv6) communicate with each other and keeps the end-to-end address transparency.
[2] Stateless NAT64 can be used in 4 different scenarios:[3] Stateless NAT64 is a replacement of SIIT (RFC 6145).
The name "IVI" represents the number 4 (IV) and 6 (VI) in roman numerals merged to represent the IPv4/IPv6 translation.
[2]