Impact has multiple fields within their reporting, here you can find a list for the associated field in Affluent
Custom Field 1: Text1
Custom Field 2: Text2
Custom Field 3: Text3
Custom Field 4: Numeric1
Custom Field 5: Numeric2
Custom Field 6: Numeric3
Custom Field 7: Money1
Custom Field 8: Money2
Custom Field 9: Money3
Custom Field 10: MP Value1
Custom Field 11: MP Value2
Custom Field 12: MP Value3
Custom Field 13: Disposition
Custom Field 14: Date1
Custom Field 15: Date2
Custom Field 16: Date3
Custom Field 17: Referral Param1
Custom Field 18: Referral Param2
Custom Field 19: Referral Param3
Custom Field 20: Referral Param4
Custom Field 21: Location Name
Custom Field 22: Location ID
Custom Field 23: Text4
Custom Field 24: Conversion Country