What is C+ fare code? I've seen it listed as C, I, W and S

Pre-accelerator the MQM for C or I is 150% of miles flown.
I'm pricing an itn and C+ is listed as S--would I earn 150% or per various fare code charts only 100%?
Per the accelerator promo, C+ will earn in addition a 75% bonus miles toward MQM (just like all other premium cabin fares), this promo only references the NAME of class not a fare code.

What's the "story"?