R= Resistor, very good for avoiding radio interferance
E (H)=Wire end size small (Big, all weather)
M (B)=Reach short (long)
40 (XX)=heat range
E (S, BY)= Massive electrode (Iridium, Protruding)
All this is from memory, so I might have screwed it up. Depending on the size of your spark plug wire ends, you'll need either REM or RHM, suggest Massive electrode unless you foul plugs alot. SHORT REACH ONLY for your standard lyc.