The meaning of a sentence is a layered structure (Hengeveld 1989) as shown in the following diagram:

1. By combining a set of participants with a situation core, a situation is constructed: .
2. By fixing the temporal coordinates of a situation, a bare proposition is constructed: .
3. By applying a basic illocution to a bare proposition, a typed proposition is constructed; it is an interrogative proposition in .
4. By applying a specific illocutionary force to a typed proposition, an utterance is constructed; it is a question in .

If, in addition to step 2, the reference of the participants is fixed – ‘your son’ and ‘Mary’ in –, the bare proposition becomes a state of affairs.

Needless to say, is, first of all, a linguist's example sentence. Similarly as with the fixing of the coordinates in step 2, one has to imagine that it is an utterance made in a particular speech situation.