Jet .. "NC" code is a ticket UA issues that is upgraded - either with points or with a Systemwide or with a 500 miler. NF is the First equivalent. I do not know what class they put on operational u/gs.
AC*SE ... not sure if what DH asked is what the answer is. I suspect there might be seperate classes of ticket as N or X? i.e. like V or W or B or Y etc. But maybe on website they are referring to N or X as not being eligible for something or other?
------------------
~ Glen ~