There are 2 test modes that can be used when working with this part of the API.
Test Mode 1
If the parameter 'test' is set to 'true' by itself, you get a simple welcome message. This can be used to verify that you are able to successfully connect to the API.
Test Mode 2
Using the GUID parameter with the Test parameter will return a web page that tells you the current version of the API you have connected to, all the possible parameters with their current values, a link to the URL that would be used by the GUID and the results of looking up the GUID that was sent