NameRegistry is an FA2-compliant smart contract (TZIP-12). All 2nd-level domains can be used as non-fungible tokens, with a few caveats:
After a domain expires, the owner's balance of the token is always
0. That means that a domain will "disappear" as a token once it expires (although the
token_id continues to be valid).
We don't implement the optional
all_tokens view, because the number of tokens is too large to be returned in one call.
When a domain changes owners, all existing operators are automatically dropped.
See the TZIP-12 specification for more information about the FA2 standard.