How to set APPX_PIVOT_YEAR?

APPX_PIVOT_YEAR determines which century Appx will add to a date item when you mask off the century portion in an input (or menu) process. In other words, if you have a date field DATE CCYYDD and a date mask of 7766, Appx will look at APPX_PIVOT_YEAR to decide which century it should stuff in the CC portion.