There are 4 different transaction types (ZumRailsType):
Fund ZumWallet - Send funds from the funding source to the Zūm Wallet.
Withdraw ZumWallet - Send funds from the Zūm Wallet and send them to the funding source.
Accounts Payable - Send funds from either the funding source or the Zūm Wallet to a user.
Accounts Receivable - Send funds from a user to either the funding source or the Zūm Wallet.