One of the most common forms of payment transactions on the Solid platform is the Card type. From an API standpoint, this is:
Transaction object > transferType > card
API reference: The Transaction Type sub-object
Under the card transferType, there are several subTypes that apply to Card transactions:
auth
When a Solid issued card has a merchant authorization request for the given amount. For example, you present your card at the gas pump to start pumping gas. Typically $200 is sent as an authorization, because the final transaction amount is unknown at the moment. The auth amount is deducted from the account balance until the transaction is captured.
authUpdate
When an auth is updated due to a change in the amount of the transaction. For example, you were authorized for $200 of gas, but you only needed $100. The authUpdate will change the amount of the transaction to $100, and return $100 to the account balance, until the transaction is captured. Another example is when your card is run at a restaurant for the amount of the bill, but then you add a tip. The authUpdate will add the tip amount to the transaction.
reversal
Reversals could occur due to various reasons, for example, when an authorized transaction is voided by the acquirer, or the transaction is not captured in a timely manner, or a reversal performed after a transaction but before settlement occurs. If a customer makes a purchase and changes their mind a short while later because they want to return the item or use a different payment method, this may result in an authorization reversal. Reversals may be full or partial.
refund
When an item from a card purchase transaction is returned, for example, and the customer requires funds to be returned to the card. In such cases, merchants send funds to customers, usually via a credit transaction. This is processed as a new and separate transaction that takes funds from the merchant account and credits it back to the customer. Refunds don't have any direct link to the original purchase. Refunds may be full or partial.