This object selects whether a newly created IPv6 filter entry uses a 64-bit or full 128-bit address match, with the device defaulting to the full 128-bit match. An administrator chooses the 64-bit option to match on IPv6 prefixes rather than exact host addresses, which can conserve limited filtering hardware resources when broad prefix matching is sufficient. For example, setting tFilter64Bitsor128 to ipv664(2) lets an administrator create a filter matching an entire /64 IPv6 prefix instead of a single specific address.