The scale of the epistemic modality goes from "Someone does not believe that X" (value 0) through "Someone believes that possibly X" to "Someone believes that X" (value 1.0).
The scale of the deontic modality goes from "Someone believes that the performer of an action must not X" (value 0) to "Someone believes that the performer of an action must X" (value 1.0).
The scale of the volitive modality goes from "Someone does not desire that X" (value 0) to "Someone desires that X" (value 1.0).
The scale of the expectative modality goes from "Someone does not plan/intend that X" (value 0) through "Someone somewhat plans/intends that X" to "Someone plans/intends that X" (value 1.0).
The scale of the potential modality goes from "X is not possible" (value 0) through "X is definitely possible" (value 1.0)