Indirect (dependent) exclamations form subordinate clauses in sentences which, taken as a whole, are statements ( cross2575. 4). They are introduced by οἷος, ὅσος, οἵως, ὡς, οἷ, ἵνα. The negative is οὐ. It is often difficult to distinguish between indirect exclamations and indirect questions introduced by οἷος or ὅσος. But observe that dependent exclamations are not introduced by the direct interrogatives ποῖος, πόσος, πῶς, etc., nor by the indefinite relatives ὁποῖος, ὁπόσος, ὅπως, etc., both of which classes of words may stand in indirect questions.
a. ὁποῖος in
b. The introductory verb is sometimes omitted; as ὦ μιαρώτατος, ἵν' ὑποδέδυ_κεν
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].