You are correct, reading the RFC just a little further than my ctrl+f found: > A host identified by an Internet Protocol literal address, version 6 [RFC3513]

You are correct, reading the RFC just a little further than my ctrl+f found: > A host identified by an Internet Protocol literal address, version 6 [RFC3513] or later, is distinguished by enclosing the IP literal within square brackets ("[" and "]").