Response to the inquiry record. Identifies the any error type.
There are three possible types of responseCode:
1. <responseCode> < 0. MWE validation error.
2. <responseCode> = 0. Transaction was successful
3. <responseCode> > 0. Transaction was declined by the provider.
One of the following: AUD, CAD, EUR, GBP, JPY, NZD, SGD, USD. This is provider dependant. Please check with MW before attempting to process transactions in any currency other than AUD.