Moving right along into § 4, we come to mood, and Rijksbaron breaks down the use of the moods in independent sentences in terms of their illocutionary force (which R. calls "various sentence types"):
(i) Declatrative sentences (negative οὐ), using the indicative (presenting a state of affairs as a fact: factual presentation), the optative + ἄν (presenting the realization of a state of affairs as possible: potential presentation), and the secondary indicative + ἄν (presenting the realization of the states of affairs as no longer possible: counterfactual presentation).
(ii) Jussive or directive sentences (negative μή), using the imperative (commanding someone to carry out the state of affairs) and subjunctive (commanding oneself with or without others to carry out the state of affairs: (ad)horative subjunctive, or in the second person plural with μή to prohibit them from carrying out the state of affairs: the prohibitive subjunctive).
(iii) Interrogative sentences. R. subdivided into the two type:
(a) yes-no question, using the indicative (wanting to know whether the state of affairs is a fact), subjunctive (in the first person, usually plural: being uncertain whether to carry out the state of affairs), and optative + ἄν (wanting to know whether the realization of the state of affairs is possible).
(b) In specifying questions, with interrogative pronouns and adverbs: indicative (seeking further information about a state of affairs considered to be a fact), subjunctive (doubting about an aspect of a state of affairs to be carried out: deliberative or dubitative subjunctive), and optative + ἅν (seeking further information about a possible state of affairs).
(iv) Wishes (negative μή), using the optative without ἄν (presenting the realization of the state of affairs as desirable and possible), and secondary indicative introduced by εἴθε or εἰ γάρ (presenting the realization of the state of affairs as desirable but no longer possible: unrealizable wish).
Note 1: Both οὐ and μή can occur in yes-no questions asking for confirmation or denial, respectively,
Note 2: All the uses of the subjunctive can be reduced to the common denominator of the voluntative subjunctive. R. promises to look at the subjunctive and optative in dependent clauses later in chapter III.
Note 3. There are different ways to express commands and wishes for pragmatic reasons.
Note 4. Specifying questions are usually called wh-questions in linguistic studies written in English.