The Transaction Type field categorises transactions based on their purpose.
Here is a list of supported Transaction Types:
EXPENSE: This type represents transactions involving costs incurred by the user. EXPENSE can be combined with Pay Type MANUAL and CARD
PAYMENT: This type denotes transactions that involve the transfer of funds from the user to another party. PAYMENT can be combined with Pay Type CARD, OUTBOUND_BANK_TRANSFER, OUTBOUND_BANK_TRANSFER_DIRECT_DEBIT
INBOUND: This type covers transactions where funds are received by the user. INBOUND can be combined with Pay Type INBOUND_BANK_TRANSFER