主辞 しゅじ素性 そせい規約 きやくでしょう
shujisoseikiyakudeshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 主辞素性規約

1. Probably a characteristic rule.; Likely a defining trait.

Polite
Presumptive
Conjecture
Linguistics