> ## Documentation Index > Fetch the complete documentation index at: https://nextgen-docs.enfuce.com/llms.txt > Use this file to discover all available pages before exploring further. # Authorisation Message Types This section provides an overview of the different authorisation messages Enfuce sends to the ledger, based on the communications we receive from the card Schemes. We transmit the information to the ledger via two interfaces — [Authorisation Request API Endpoint](https://nextgen-docs.enfuce.com/guides/transaction-lifecycle/authorisation/authorisation-request-message) and [Transaction Event Webhook](https://nextgen-docs.enfuce.com/guides/transaction-lifecycle/authorisation/transaction-event-webhook).

Authorisation Type	Message Category	Description
Initial Authorisation	`INITIAL\_AUTHORIZATION`	An initial authorisation is the first request sent to approve a transaction and reserve funds on the cardholder’s account. It represents either the final transaction amount (for standard purchases) or an estimated amount (for scenarios such as hotels, car rentals, or fuel). The ledger responds with the authorisation outcome which can be approved, declined, or partially approved. A successful initial authorisation results in an authorisation hold for the approved amount.
Incremental Authorisation	`INCREMENTAL\_AUTHORIZATION`	An incremental authorisation is an additional request, submitted after the initial authorisation, to increase the total authorised amount. This is commonly used where the final amount is not initially known. The ledger responds with the authorisation outcome which can be approved, declined, or partially approved. Each incremental authorisation adds to the existing hold and must be linked to the original authorisation.
Adjustment	`ADJUSTMENT`	An adjustment (partial reversal) decreases the amount of an existing authorisation to reflect an updated transaction value that better aligns with the final expected clearing amount. The ledger must apply the adjustment amount in accordance with the Scheme rules and partially release the funds back to the cardholder’s available balance; they cannot decline the request.
Reversal	`REVERSAL`	An authorisation reversal cancels the previously approved authorisation hold, when the funds are no longer required (for example, a cancelled transaction). This releases the funds previously held back to the cardholder’s available balance. The ledger must apply the reversal in accordance with scheme rules, and cannot decline the request.
PIN Change Request	`PIN\_MANAGEMENT`	PIN management request is a request to change a cardholder’s Personal Identification Number (PIN). These requests are processed securely via the card Schemes and ensure that the updated PIN can be used for authentication in card-present transactions. The request can come with associated fees. The ledger can either approve or decline the request after verifying whether the functionality is supported; the cardholder's account must have sufficient balance to cover the fee.
PIN Change Request Reversal	`PIN\_MANAGEMENT\_REVERSAL`	A PIN management reversal request refers to the reversal of a previously initiated PIN change request, ensuring that the card’s PIN remains unchanged in cases where the original request could not be completed or needs to be cancelled.
Balance Enquiry	`BALANCE\_INQUIRY`	A balance enquiry is a request made to check the balance of a cardholder’s account, without initiating a financial transaction. This can occur at ATMs, POS terminals, or through other channels. The ledger responds with the relevant balance information, enabling the cardholder or merchant to determine whether sufficient funds are available.
Declined Authorisation	`DECLINED\_AUTHORIZATION`	The scheme declined the transaction on behalf of Enfuce in the Stand-In Processing (STIP) mode, when the response returned by the processor has either timed out or the processor has returned a faulty message.
Purge Authorisation	`PURGE\_AUTHORIZATION`	All excluded authorisations are purged (that is, released) after a specific period. A purged authorisation request is not included in a `FINANCIAL` message. A partially approved payment is also purged, where only the amount excluded in the clearing message is purged.
Void Authorisation	`VOID\_AUTHORIZATION`	When an initial authorisation or an incremental authorisation request times out, we generate a `VOID_AUTHORIZATION` message because we do not know whether your system has blocked the authorisation amount or whether no action has been taken. A void authorisation message refers to the event `id` to cancel the specific message and not the entire transaction history.

## Related Topics * [Authorisation Request API Endpoint](https://nextgen-docs.enfuce.com/guides/transaction-lifecycle/authorisation/authorisation-request-message) * [Transaction Event Webhook](https://nextgen-docs.enfuce.com/guides/transaction-lifecycle/authorisation/transaction-event-webhook)