RS i think is just the R from
RM and S from T
S or D
S somewhere i had a list of what the suzuki model letters stood for.
RM- racing machine/real motorcrosser
IT - international trials
DS - dual sport/dirt special
RH - real horsepower
PE - pure enduro or production enduro
SP - soft powered/special purpose
TS -two stroke/too slow
RV - recreational vehicle