When a purchase is made by a Member with an active Merchant, the Merchant acquiring bank or the financial institution that processes payments on behalf of the Merchant needs to confirm with the Member's card issuing bank that their card has the required funds to make a purchase.
In most cases, the Merchants acquiring bank and the Members card issuing bank are different to one another, meaning that the transaction data needs to be sent to the schemes to complete a validation process. It is during this process that the "AUTH" or real time transaction appears in the portal because the Merchant acquiring bank and the Member card issuing bank are different, and the schemes have visibility of the "AUTH" or real time transaction.
However, when the Merchant's acquiring bank and the Member card issuing bank is the same, it is called "ON US" (e.g. an ANZ Bank Merchant acquirer and an ANZ Bank issued Member card). This is because the bank is able to validate the Member's available funds internally, and they do not need to expose the transaction data immediately to the schemes for validation. As a result, the transaction is not sent to the Member until the bank exposes the transaction to the schemes some 3-5 business days later with a "CLR" or cleared transaction. It is at this point that the transaction appears in the portal.