An informal term for literally just looking at the output and manually scanning for errors. Unless you’re a hardcore practitioner of Test Driven Development[TDD], it’s likely that you’ve done this and it’s certainly what I was doing when I first started experimenting with iXML. It’s low risk while you’re learning something new and the inputs and outputs are small and simple - and the software isn’t in production - but as complexity increases, manual checks usually become more time-consuming and risky and the odds are that you will start missing mistakes. Eventually you’re going to need to put something more robust in place.