Halliday & Matthiessen (2014: 171):
Whether they are dependent or downranked, ‘bound’ clauses may be either ‘finite’ or ‘non-finite’. ‘Finite’ clauses are typically introduced by a binder (or relative/interrogative item), and have the same modal structure as ‘declarative’ clauses, i.e. Mood: Subject ^ Finite – even when they are reports of questions …