Test Identifier - It's the string of digits, letters and dashes. Every test has a unique test ID:
If you see a non-clickable image somewhere, you can type testmy.net/db/ followed by this ID in the image to get more detail on a test, e.g. http://testmy.net/db/wMiM9vIQX
If you see "TID" written somewhere less obvious, post a screenshot for us to have a look at.