YR187L&1: Orange Alcantara
YR187L&237: Orange Alcantara
---Maybe the &1 and &237 determine if it's trimmed in Black Leather or Black Alcantara?
NH188L&1 Black Alcantara
NH188L&199 Black Alcantara
---This is my best guess, it could be black jersey but I'm pretty sure it's black alcantara, again not sure on the &1 and &199
R124L Red (not sure if alcantara or Jersey fabric) - See my EDIT below
B93L: Blue Alcantara
---I actually have never seen this code, it's always been &1 and &14 in my research
B93L&1: Blue Alcantara
B93L&14: Blue Alcantara
Because all of the Type-S ones have &1 my best guess is the &1 is black leather trim
I know it doesn't give you much more than you already had but it's a start
EDIT: So it looks like NH188L, YR187L, and B93L designations without a &1 or &X were the designations used for the 02+ Type-S seats, all 3 have different part numbers than their 97-99 counterparts so something is different, just not sure what. Now for the 5spd NSX-R looks like the seats were either all black or all red. But for the 02+ NSX-R you could get either black or red outer with either red or black cushions. But R124L is the code, again don't know how to tell the difference between jersey fabric or alcantara based on the color code.