Constituent tree

The Link Grammar parser can generate a Penn tree-bank style phrase structure. For example:

(S (NP The commie) (VP was (ADJP red)) .)

The phrase structure as output by RelEx is identical to that output by the link grammar parser; RelEx does not modify it. RelEx does use the phrase structure in various ways, including the Hobbs algorithm anaphora resolution algorithm.

There are a number of different possible phrase types:

Description	Penn type	Example
adjective phrase	ADJP
adverb phrase	ADVP
sentence clause	S	(S (NP (NP The commie) , (SBAR (WHNP who) (S (VP was (ADJP red)))) ,) (VP faded (PRT away)) .)
inverted subject-verb clause	SINV
noun phrase	NP
particle	PRT	(S (NP (NP The commie) , (SBAR (WHNP who) (S (VP was (ADJP red)))) ,) (VP faded (PRT away)) .)
prepositional phrase	PP	(S (NP There) (VP were (NP (NP three) (PP of (NP them)))) .)
quantifier phrase	QP
root clause	S
subordinate clause	SBAR	(S (NP (NP The commie) , (SBAR (WHNP who) (S (VP was (ADJP red)))) ,) (VP faded (PRT away)) .)
verb phrase	VP
wh-adverb	WHADVP	(S (NP The bridge) (VP was (ADJP unfinished)) (SBAR (WHADVP when) (S (NP it) (VP collapsed))) .)
wh-noun	WHNP	(S (NP (NP The commie) , (SBAR (WHNP who) (S (VP was (ADJP red)))) ,) (VP faded (PRT away)) .)
wh-prep	WHPP	(S (NP The commie (SBAR (WHPP to (WHNP whom)) (S (NP I) (VP was))) speaking) (VP was (ADJP red)) .)