identification mark

19 LETTERS · STARTS WITH I

identification mark is a valid 19-letter word worth 30 points in Scrabble and 34 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

I1D2E1N1T1I1F4I1C3A1T1I1O1N1M3A1R1K5

1 + 2 + 1 + 1 + 1 + 1 + 4 + 1 + 3 + 1 + 1 + 1 + 1 + 1 + 0 + 3 + 1 + 1 + 5 =30 PTS

DOUBLE WORD → 60TRIPLE WORD → 90

MEANING

What does identification mark mean?