HANDICAP GURU: Meaning of codes after Handicaps.
Q: What do the coded letters represent after a plarepresent after a player's Index from the USGA's Golf Handicap and Information Network (GHIN)?
A: There are three letters you might see follow an Index. "L" means the
lndex is for local use only. An "R" means it has been reduced because of extremely low tournament scores. "M" means it was modified temporarily
by the Handicap Committee.
from DEAN KNUTH, former senior director of the USGA Handicap Department.
From Golf Digest March 2013, page 58