Linguistic modality includes necessity (also known as deontic modality, abbreviated in the values as Deon) and possibility, each with a situational (objective, fact-based) and an epistemic (subjective, speaker-specific) variant.[1] Epistemic necessity indicates that the certainty of the information described is based on the speaker’s personal opinion.[2] Epistemic necessity can be expressed through the use of verbal affixes or clitics, verbal constructions (such as periphrasis), and other markers, such as particles, adverbials, nouns, adjectives, and phrase- or clause-level clitics. These strategies may serve multiple functions, in addition to expressing epistemic necessity.

Types:

EpsDeonAff: Epistemic necessity is expressed through the use of verbal affixes.[3]

EpsDeonV:  Epistemic necessity is expressed through the use of verb constructions.

EpsDeonElse: Epistemic necessity is expressed through a strategy other than verbal affixes and verb constructions.[4]

When a language displays more than one strategy, multiple values can be listed. If one strategy is dominant, a slash (/) can separate the two values, with the dominant value appearing first; if neither is dominant, they are listed with an ampersand (&) separating the two.

[1] Example of situational necessity: I have to go. Example of epistemic necessity: He has to be here (= I think he is here). Situational possibility refers to a situation in which an agent is either capable of an action, allowed to perform it, or faces no objective obstruction from performing it. Epistemic possibility refers to a situation assumed by the speaker.

[2] Consider the following example: It’s so late she must be home by now (= I’m sure she’s home).

[3] This value applies even if the use of verb affixes is not the only strategy available in the language for the expression of epistemic necessity.

[4] This should be detailed in the commentary.