They used to call them "Silver Zee"'s, but basiclly it's a "Z" train that is close to falling behind schedule. Once it falls behind schedule it becomes a "Golden Zee" and the hottest thing on the railroad by far. The color name refers to the color of the train title on the dispatch screen. Normally a train name is bright white. But if it gets close to falling behind schedule, the name dims a bit and appears to be light gray or "silver". If the train does fall behind it goes to yellow or "golden". Now if a train gets way behind it will go to red, but I've never have heard of a "Bloody Z".