phrase-structure rule

21 LETTERS · STARTS WITH P

phrase-structure rule is a valid 21-letter word worth 26 points in Scrabble and 31 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

P3H4R1A1S1E1-0S1T1R1U1C3T1U1R1E1R1U1L1E1

3 + 4 + 1 + 1 + 1 + 1 + 0 + 1 + 1 + 1 + 1 + 3 + 1 + 1 + 1 + 1 + 0 + 1 + 1 + 1 + 1 =26 PTS

DOUBLE WORD → 52TRIPLE WORD → 78

MEANING

What does phrase-structure rule mean?