Labeling in linguistics
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- 1 Lexical categories / POS
- 2 Dependencies
Lexical categories / POS
Tagsets are usually primarily based on parts of speech, sometimes with common linguistic features added.
The basic few POS tags are agreed on, but there is always discussion possible about the detail, special cases, the degree of normalisation (have specific tags vs. have tags essentially with features). This also affects the ways it can or cannot tag languages other than English.
C5, a.k.a BNC basic
61 tags See e.g. 
The same as C7 except for handling of punctuation.
C7, a.k.a BNC enriched
146 tags See e.g. 
Various versions, current is C8.
The latest program seems to be referred to as CLAWS4. See 
CLAWS1 tagset - 132 tags - 
CLAWS2 tagset - 166 tags - 
C5 - 
C6 - 
C7 - 
C8 - 
...usually meaning 'not generally used'. See also corpora.
Stanford dependency representation
Broad overview: https://universaldependencies.org/u/dep/