place. Speakers wanting a long turn, for example to tell a story or describe important news, must first establish that others will not intervene during the course of the telling through some form of preface and approval by the listener (a so-called go-ahead). The preface and its associated go-ahead comprise a pre-sequence. Conversations cannot be appropriately ended by 'just stopping', but require a special closing sequence.

The model also leaves puzzles to be solved, for example concerning how turn boundaries are identified and projected,