Sale and Authorization Only
The action code “captureToo” allows you to capture the transaction at the same time you authorize it. Use this if you ship same day and there is no variation in amount. Omitting the “captureToo” action code will be treated as a Authorization Only request, the capture only message marks Auth transactions for settlement.

For testing set the following fields after selecting the "Try It" button
externalReferenceID = Unique record identifier for processing - you assign Numeric Min = 16 Max 19
transactionDate = Set to UTC timezone, Format 2020-08-25T17:01:01

Click Try It! to start a request and see the response here!