The Penn Treebank Tagset

Similarly to the SUSANNE Corpus Tagset, the Penn Treebank Tagset consists of two main parts. There is the syntactic tagset and the POS tagset.

The syntactic tagset

ADJPAdjective phrase
ADVPAdverb phrase
NPNoun phrase
PPPrepositional phrase
SSimple declarative clause
SBARClause introduced by subordinating conjunction or 0 (see below)
SBARQDirect question introduced by wh-word or wh-phrase
SINVDeclarative sentence with subject-aux inversion
SQSubconstituent of SBARQ excluding wh-word or wh-phrase
VPVerb phrase
WHADVPWh-adverb phrase
WHNPWh-noun phrase
WHPPWh-prepositional phrase
XConstituent of unknown or uncertain category
Null elements
*„Understood“ subject of infinitive or imperative
0Zero variant of that in subordinate clauses
TTrace—marks position where moved wh-constituent is interpreted
NILMarks position where preposition is interpreted in pied-piping contexts

The POS tagset

CCCoordinating Conjunction
CDCardinal Number
DTDeterminer
EXExistential there
FWForeign word
INPreposition/subordinating conjunction
JJAdjective
JJRAdjective, comparative
JJSAdjective, superlative
LSList item marker
MDModal
NNNoun, singular or mass
NNSNoun, plural
NNPProper noun, singular
NNPSProper noun, plural
PDTPredeterminer
POSPosessive ending
PRPPersonal pronoun
PPPosseive pronoun
RBAdverb
RBRAdverb, comparative
RBSAdverb, superlative
RPParticle
SYMSymbol (mathematic or scientific)
TOto
UHInterjection
VBVerb, base form
VBDVerb, past tense
VBGVerb, gerund/present participle
VBNVerb, past participle
VBPVerb, non-3rd person singular present
VBZVerb, 3rd person singular present
WDTwh-determiner
WPwh-pronoun
WP$Possesive wh-pronoun
WRBwh-adverb
#Pound sign
$Dollar sign
.Sentence-final punctuation
,Comma
:Colon, semi-colon
(Left bracket character
)Right bracket character
"Straight double quote
Left open single quote
Left open double quote
Right closed single quote
Right closed double quote

This list is taken from the HTML version of ‚Building a large annotated corpus of English: the Penn Treebank‘ by Mitchell P. Marcus, Mary Ann Marcinkiewicz, Beatrice Santorini which also contains a lot of useful information about the Penn Treebank.