the clause expressing the causally antecedent proposition in a causal, conditional, concessive, concessive conditional, or comparative conditional construction; or the proposition or event denoted by the clause. Example: in If you press this button, the door will open, If you press this button is the protasis; the door will open is the apodosis. Since the conditional relations are defined in terms of both logical implication and causal relation, the semantic use of 'protasis' can be distinguished as 'protasis proposition' or 'protasis event'. (Section 17.3.1)