What are the Payflow Pro transaction types?

Payflow Pro has several different transaction types. 

When creating credit card transactions with Payflow Pro, you must specify the transaction type as follows: 

• S - Sale: Charges the specified amount against the account and marks the transaction for immediate funds transfer during the next settlement period. PayPal performs settlement for each merchant daily. 
• A - Authorization: Authorizes transactions that may be captured later. A Delayed Capture (D) transaction must be issued to capture the original authorization.
• D - Delayed Capture: Used to capture a previously Authorized (A) transaction. The transaction is scheduled for settlement during the next settlement period. This provides support for delayed order fulfillment. 
• C - Credit: Returns the specified amount to the account holder. You don't need to have the credit card number available if you have the original PayPal reference ID (PNREF) that was issued with the transaction. If you issue a credit with the PNREF without specifying an amount, PayPal uses the amount of the original transaction.
• V - Void: A void is the reversal of a charge before the settlement process. Voided transactions can't be settled. A void doesn't guarantee the release of the authorization (hold on funds) on the cardholder's account. 
• F - Voice Authorization: Payflow Pro may perform a voice authorization transaction after getting an approval code from the cardholder's issuing bank. This offline process establishes the transaction as an item that can be settled. (Voice authorizations aren't available when you're using PayPal as a processor).
• I - Inquiry: Payflow Pro may perform an inquiry transaction to check the result and status of a transaction. 
• N - Duplicate Transaction: A type N transaction represents a duplicate transaction (version 4 SDK or HTTPS interface only) with a PNREF that is the same as the original. Transaction Type N appears only in the PayPal Manager user interface and will never settle. The duplicate occurs because the same X-VPS-REQUEST-ID was used on multiple transactions.