Amount to sell (quantity)
Optional
expiration_ExpirationTimestamp in Unix time. Note: will be rounded down to the nearest hour
Optional
feesInclusion of either maker or taker fees
Optional
split_SplitFees dictates whether fees will be split between maker & taker, set split_fees to true when submitting signing to v3 endpoints and vice versa for v1
Ethereum address of the submitting user
Fee-exclusive amount to buy the asset