( 3)a. focus: informative and newsy material; material that completes an open proposition provided by ground and/or the discourse context b. ground: non-informative and expected material; material that provides an open proposition to be completed by focus c. topic: an entity presented as something the message is 'about'; an entity that the hearer is expected or directed to give attention to as the location of information update d. tail: the complement of the topic in the ground (i.e., tail = ground − topic) e. comment: the complement of the topic in the utterance (i.e., comment = link + focus) An utterance may consist of focus only, focus-tail, focus-topic, or focus-tail-topic; it is impossible, on the other hand, for an utterance to consist of ground elements only.
an utterance may be topic-less or ground-less, but cannot be all-ground.