Penn Treebank II tag set
Pattern and MBSP assign meaningful tags to words and groups of words in a sentence. Each tag is a short code (such as "DT" for "determiner").
The tag set is based on the Penn Treebank Tagging Guidelines [pdf].
Part-of-speech tags
Part-of-speech tags are assigned to a single word according to its role in the sentence. Traditional grammar classifies words based on eight parts of speech: the verb (VB), the noun (NN), the pronoun (PR+DT), the adjective (JJ), the adverb (RB), the preposition (IN), the conjunction (CC), and the interjection (UH).
| Tag | Description | Example |
| CC | conjunction, coordinating | and, or, but |
| CD | cardinal number | five, three, 13% |
| DT | determiner | the, a, these |
| EX | existential there | there were six boys |
| FW | foreign word | mais |
| IN | conjunction, subordinating or preposition | of, on, before, unless |
| JJ | adjective | nice, easy |
| JJR | adjective, comparative | nicer, easier |
| JJS | adjective, superlative | nicest, easiest |
| LS | list item marker | |
| MD | verb, modal auxillary | may, should |
| NN | noun, singular or mass | tiger, chair, laughter |
| NNS | noun, plural | tigers, chairs, insects |
| NNP | noun, proper singular | Germany, God, Alice |
| NNPS | noun, proper plural | we met two Christmases ago |
| PDT | predeterminer | both his children |
| POS | possessive ending | 's |
| PRP | pronoun, personal | me, you, it |
| PRP$ | pronoun, possessive | my, your, our |
| RB | adverb | extremely, loudly, hard |
| RBR | adverb, comparative | better |
| RBS | adverb, superlative | best |
| RP | adverb, particle | about, off, up |
| SYM | symbol | % |
| TO | infinitival to | what to do? |
| UH | interjection | oh, oops, gosh |
| VB | verb, base form | think |
| VBZ | verb, 3rd person singular present | she thinks |
| VBP | verb, non-3rd person singular present | I think |
| VBD | verb, past tense | they thought |
| VBN | verb, past participle | a sunken ship |
| VBG | verb, gerund or present participle | thinking is fun |
| WDT | wh-determiner | which, whatever, whichever |
| WP | wh-pronoun, personal | what, who, whom |
| WP$ | wh-pronoun, possessive | whose, whosever |
| WRB | wh-adverb | where, when |
| . | punctuation mark, sentence closer | .;?* |
| , | punctuation mark, comma | , |
| : | punctuation mark, colon | : |
| ( | contextual separator, left paren | ( |
| ) | contextual separator, right paren | ) |
Chunk tags
Chunk tags are assigned to groups of words that belong together (i.e. phrases). The most common phrases are the noun phrase (NP, for example the black cat) and the verb phrase (VP, for example is purring).
| Tag | Description | Words | Example | % |
| NP | noun phrase | DT+RB+JJ+NN + PR | the strange bird | 51 |
| PP | prepositional phrase | TO+IN | in between | 19 |
| VP | verb phrase | RB+MD+VB | was looking |
9 |
| ADVP | adverb phrase | RB | also |
6 |
| ADJP | adjective phrase | CC+RB+JJ | warm and cosy | 3 |
| SBAR | subordinating conjunction | IN | whether or not |
3 |
| PRT | particle | RP | up the stairs | 1 |
| INTJ | interjection | UH | hello |
0 |
The IOB prefix marks whether a word is inside or outside of a chunk.
| Tag | Description |
| I- | inside the chunk |
| B- | inside the chunk, preceding word is part of a different chunk |
| O | not part of a chunk |
A prepositional noun phrase (PNP) is a group of chunks starting with a preposition (PP) followed by noun phrases (NP), for example: under the table.
| Tag | Description | Chunks | Example |
| PNP | prepositional noun phrase | PP+NP | as of today |
Relation tags
Relations tags describe the relation between different chunks, and clarify the role of a chunk in that relation. The most common roles in a sentence are SBJ (subject noun phrase) and OBJ (object noun phrase). They link NP to VP chunks. The subject of a sentence is the person, thing, place or idea that is doing or being something. The object of a sentence is the person/thing affected by the action.
| Tag | Description | Chunks | Example | % |
| -SBJ | sentence subject | NP | the cat sat on the mat |
35 |
| -OBJ | sentence object | NP+SBAR | the cat grabs the fish |
27 |
| -PRD | predicate | PP+NP+ADJP | the cat feels warm and fuzzy |
7 |
| -TMP | temporal | PP+NP+ADVP | arrive at noon |
7 |
| -CLR | closely related | PP+NP+ADVP | work as a researcher |
6 |
| -LOC | location | PP | live in Belgium |
4 |
| -DIR | direction | PP | walk towards the door |
3 |
| -EXT | extent | PP+NP | drop 10 % |
1 |
| -PRP | purpose | PP+SBAR | die as a result of |
1 |
Anchor tags
Anchor tags describe how prepositional noun phrases (PNP) are attached to other chunks in the sentence. For example, in the sentence, I eat pizza with a fork, the anchor of with a fork is eat because it answers the question: "In what way do I eat?"
| Tag | Description | Example |
| A1 | anchor chunks that corresponds to P1 | eat with a fork |
| P1 | PNP that corresponds to A1 | eat with a fork |
Occurence estimate
The given percentages for chunk and relations tags are based on tenfold cross validation on sections 10 to 19 of the WSJ Corpus of the Penn Treebank II by Sabine Buchholz, from which we derived a rough indication. The estimate means that if a 100 chunk tags are found, about 50 would be NP tags and 35 would have a SBJ relation tag. About 30 of the chunks would be tagged as NP-SBJ, and 15 as NP-OBJ.
Reference: Buchholz, S. (2002). Memory-Based Grammatical Relation Finding. ILK, Tilburg University.