If you are copying, you can use straight or reverse collated in any tray as you can stipulate face up or face down output. However, with printing, you cannot stipulate this. If you are using trays 1, 2, 3, or 4, with printing, use the reverse collated carbonless paper. If you are using tray 5, 6 or 7, then you can use the straight collated carbonless paper. NOTE: "XEROX Premium Digital Carbonless stock is not intended for sole usage, nor is it recommended to exceed this monthly print volume without interim service. " (Monthly print volume not to exceed 125K. ) **"NCR" is a brand name of carbonless paper and is a commonly used term when referring to carbonless paper Special cleaning procedures are required. Please contact your Xerox Service Representative...