Full URI of the resource (domain derived from this)
OptionalstatementOptional statement explaining the sign-in purpose
OptionalversionSIWx version (defaults to "1")
Network in CAIP-2 format (e.g., "eip155:8453")
OptionalexpirationExpiration time (auto-set to +5 minutes if not provided)
OptionalsignaturePreferred signature scheme
Options for declaring SIWx extension on server.