information packaging in which a particular piece of information (the focus) is equated with the 'open slot' in a presupposed open proposition; and the construction that expresses that information packaging. The presupposed open proposition may be evoked by an alternative proposition that differs from the identificational construction by only the focus. Example: in It was Ollie who was playing the piano, the information in the identificational construction is divided into the presupposed open proposition 'X was playing the piano', and the focused information Ollie, and what is being asserted is 'X = Ollie'. The term 'focus' is sometimes used as a synonym for 'identificational', but this term is used differently here. (Sections 10.1.2, 11.1, 11.4.1)