McNamara, Paul and Frederik Van De Putte, "Deontic Logic", The Stanford Encyclopedia of Philosophy (Fall 2022 Edition), Edward N. Zalta & Uri Nodelman (eds.), URL = https://plato.stanford.edu/archives/fall2022/entries/logic-deontic/>.permissible (permitted)impermissible (forbidden, prohibited)obligatory (duty, required)omissible (non-obligatory)optionalnon-optionalmustought supererogatory (beyon..