Miller's spot on. The terms LUP and CUP didn't exist until we starting using transducers to measure pressure--at which time it was determined that the old psi readings weren't accurate. In order to distinguish between the inaccurate crusher values and the new transducer values, the terms LUP and CUP replaced the old crusher psi values, depending on whether the measurements were made with lead or copper crushers. From then on, psi (at least in this country) meant only those values derived from transducer measurements. The problem comes when you read old literature, when crushers were still being used, and figures that should be interpreted as either LUP or CUP are expressed as psi.
