Martin (1992: 413):
Table 6.19. Congruent and metaphorical realisations of interpersonal meanings  mood proposition: congruent statement declarative He’s here question interrogative Is he here? metaphorical statement probability It may be that… question usuality It is usual that… statement projection I reckon… question projection Don’t you think…
 Interpersonal metaphors of mood involve
- a speech function (semantics) being realised by a projecting clause (grammar), as in I urge you to… or
- a speech function (semantics) being realised by an incongruent mood choice (grammar), as when a command is realised by indicative instead of imperative mood; see Halliday & Matthiessen (2004: 626-35).
 Interpersonal metaphors involving probability and usuality are metaphors of modality, not metaphors of mood.
 This instance of modality combines the congruent grammatical realisation (implicit subjective may) with the metaphorical (explicit objective it's x that).
 This is a metaphorical grammatical realisation of modality (modalisation: usuality; explicit objective orientation).
 This is a metaphorical grammatical realisation of modality (modalisation: probability; explicit subjective orientation).