reference system

NOUN /rɛfərəns_'sɪstəm/
16 LETTERS · STARTS WITH R

reference system is a valid 16-letter word worth 25 points in Scrabble and 27 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
R1E1F4E1R1E1N1C3E1S1Y4S1T1E1M3
1 + 1 + 4 + 1 + 1 + 1 + 1 + 3 + 1 + 0 + 1 + 4 + 1 + 1 + 1 + 3 =25 PTS
DOUBLE WORD → 50TRIPLE WORD → 75
MEANING

What does reference system mean?