When you make an API call with logging enabled (either through, the API EnabledLogging property on the transaction or by turning on the ProntoServ setting in the ProntoConfig.ini file), XML files will show up in this section.  Generally there are two XML files for each call.  Once for the Request and one for the Response.  This can be very help to see the actual data that your service client's API code is sending into Pronto and exactly what is being returned from the server.

The file name for each uses the following configuration:

[API Method Name]-[Reponse/Request]-[ServerName]-[Date/Time].xml

These logs are separated by Account.