Herbert Weir Smyth, A Greek Grammar for Colleges

a. In reference to future time: τῶν πρα_γμάτων τοὺς βουλευομένους (ἡγεῖσθαι δεῖ), ““ἵν᾽ ἃ_ν ἐκείνοις δοκῇ, ταῦτα πρά_ττηται” men of counsel must guide events in order that what they resolve shall be accomplished” D. 4.39.

b. In reference to general present time: ““οὐδ᾽, ἐπειδὰν ὧν ἂν πρίηται κύ_ριος γένηται, τῷ προδότῃ συμβούλῳ περὶ τῶν λοιπῶν ἔτι χρῆται” nor when he has become master of what he purchases, does he any longer employ the traitor to advise him concerning his plans for the future” D. 18.47. But the indicative may occur (D. 22.22).