SCValTypeXdr

// 32 bits is the smallest type in WASM or XDR; no need for u8/u16.
SCV_U32 = 3,
SCV_I32 = 4,

// 64 bits is naturally supported by both WASM and XDR also.
SCV_U64 = 5,
SCV_I64 = 6,

// Time-related u64 subtypes with their own functions and formatting.
SCV_TIMEPOINT = 7,
SCV_DURATION = 8,

// 128 bits is naturally supported by Rust and we use it for Soroban
// fixed-point arithmetic prices / balances / similar "quantities". These
// are represented in XDR as a pair of 2 u64s.
SCV_U128 = 9,
SCV_I128 = 10,

// 256 bits is the size of sha256 output, ed25519 keys, and the EVM machine
// word, so for interop use we include this even though it requires a small
// amount of Rust guest and/or host library code.
SCV_U256 = 11,
SCV_I256 = 12,

// Bytes come in 3 flavors, 2 of which have meaningfully different
// formatting and validity-checking / domain-restriction.
SCV_BYTES = 13,
SCV_STRING = 14,
SCV_SYMBOL = 15,

// Vecs and maps are just polymorphic containers of other ScVals.
SCV_VEC = 16,
SCV_MAP = 17,

// Address is the universal identifier for contracts and classic
// accounts.
SCV_ADDRESS = 18,

// The following are the internal SCVal variants that are not
// exposed to the contracts.
SCV_CONTRACT_INSTANCE = 19,

// SCV_LEDGER_KEY_CONTRACT_INSTANCE and SCV_LEDGER_KEY_NONCE are unique
// symbolic SCVals used as the key for ledger entries for a contract's
// instance and an address' nonce, respectively.
SCV_LEDGER_KEY_CONTRACT_INSTANCE = 20,
SCV_LEDGER_KEY_NONCE = 21