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