I was having trouble with my computer. So I called Harold, the computer guy, to come over. Harold clicked a couple of buttons and solved the problem. He gave me a bill for a minimum service call. As he was walking away, I called after him, "So what was wrong?" He replied, "It was an ID ten T error. I didn't want to appear stupid, but I nonetheless inquired, "An ID ten T error? what's that, in case I need to fix it again?" Write it down, I think you will figure it out." Harold said. So I wrote it down: ID10T