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:
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.
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.
When an authorized transaction is voided by the acquirer, or the transaction is not captured in a timely manner.
When an item from a card purchase transaction is returned, for example, and the customer requires funds to be returned to the card.