identification thread

21 LETTERS · STARTS WITH I

identification thread is a valid 21-letter word worth 30 points in Scrabble and 32 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

I1D2E1N1T1I1F4I1C3A1T1I1O1N1T1H4R1E1A1D2

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

DOUBLE WORD → 60TRIPLE WORD → 90

MEANING

What does identification thread mean?