Lexical richness indices (Brunet's W, Honoré's R) — always available.
Calendar month in local time, "YYYY-MM".
Morphological (proxy). null/unavailable when no classifier for the language.
Phonological — only when a dictionary is supplied.
True when the month has too little data to trust the diversity figures.
Syntactic. null/unavailable when no closed-class data for the language.
Semantic — the headline measure.