Linguistic modality includes necessity and possibility (Psbl), each with a situational (Sit) and an epistemic (Ep) variant. Situational modality indicates that that described information is based on objective information, while epistemic refers to the speaker’s opinions.[1]

Some language use different strategies to express situational and epistemic modality, while others do not. Overlap between the two types may be partial or total. Partial overlap refers to the use of identical lexical or grammatical strategies[2] with distinctions in morphology or word order.

This parameter considers the degree of distinction between situational and epistemic possibility (Psbl).

Types:

NoPsbl: Possibility cannot be expressed through verbal modality.[3]

PsblSit=Ep: There is no distinction between situational and epistemic possibility in terms of verbal modality.

PsblSit~Ep: Situational and epistemic possibility are partially distinguished in terms of verbal modality.[4]

PsblSitNonEp: Situational and epistemic possibility are totally distinguished in terms of verbal modality.

[1] 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. Examples include The boy can drive a car. Epistemic possibility, on the other hand, refers to a possibility as determined by the speaker, such as The boy may be home by now.

[2] This may refer to the same auxiliary or the same affix, for example.

[3] This value applies to the expression of modality in a main clause containing a subordinate clause, as seen in examples such as It’s possible that I... Such constructions do not constitute verbal modality, but rather logical modality, which is not addressed in this parameter.

[4] This should be detailed in the commentary.