QTR-Quadtone RIP

Could anyone explain the paper/ink curve codes as set out below please.

I am using W7, 2100 and a choice of Epson PK and MK blacks.

My choices in the QTR interface are:-
                        UCmk-MEntradaNatural- .......
                        UC-EnhMatte-........... etc.
                        UC-PremierFineArt-......etc.
                           and various UCpk combinations
Questions

         What is MEntradaNatural ?
         Why no UCmk for EEnhMatte

The paper I have to hand is Epson Archival Matte, so which curve setup would be appropriate for this paper, or would I need to use a different paper for the 2100 using UCmk (Epson T0348, Matte Black)