• “Proposition operators”: these are operators capturing the grammatical means by which the speaker can express his personal evaluation of or attitude towards the propositional content. One may think of “subjective” modalities through which the speaker expresses his belief or disbelief in the content of the proposition, his hope or wish that the proposition may come true, and the source through which he has obtained the information contained in the proposition. All these operators thus relate the content of the proposition to the subjective world of the speaker.
- Dik (1989), a pag.58-59

Depending on their domain of operation, FG [Functional Grammar] recognizes the following types of operators: (2) a. Ω : term operators b. π1 : predicate operators c. π2 : predication operators d. π3 : proposition operators e. π4 : illocutionary operators […].
- Dik (1989), a pag.137-138

Proposition operators capture the grammatical means through which S [Speaker] can specify his attitude towards the propositional content […]. This attitude may concern S’s personal assessment of, or his personal commitment to the propositional content Xi, or it may give an indication of the kind of evidence that S has to warrant the correctness of the propositional content. The following semantic distinctions seem to be the most important in the field of these propositional modalities: (17) ‘Subjective’: the source of S’s evaluation is Personal opinion: it is S’s personal opinion that Xi is certain/probable/possible; Volition: it is S’s wish/hope that Xi is/will be realized. ‘Evidential’: the source of S’s proposition is Experience: S concludes that Xi on the basis of previous personal experience [“experiental”]; Inference: S infers Xi on the basis of available evidence [“inferential”]; Hearsay: S signals that he has heard Xi from someone else [“quotative”, “reportative”].
- Dik (1989), a pag.251