vaultIdfrom which sold funds are taken, and the
vaultIdto which bought funds should arrive), the two relevant
assetId,the two relevant (quantized)
expirationTimestampof the order (hours since epoch), and a
nonce(to prevent replay attacks).
assetIdof the two orders match (i.e. bought
assetIdof one is the sold
assetIdof the other)
starkKeythat corresponds to the order's
vaultIdis sufficient to fulfill the trade.
expirationTimestampof the order refers to the future.