Group and phrase complexes thus serve to develop single elements within a clause (or, if these complexes are embedded, within a group or phrase), serving the same function as a simple group or phrase would. Textually, this means there is a single message; interpersonally, it means there is a single proposition or proposal; and experientially, it means that there is a single figure. Here are some further examples:
In anyone of these examples, the complexing could be 'upgraded' to clause rank; but this would create two messages, two propositions (proposals), and two figures. Thus there is a clear semantic difference between the following two variants:
Note that we have to differentiate group and phrase complexes from clause complexes involving ellipsis. In clause complexes where the Subject or the Subject and the Finite have been ellipsed in a continuing clause, it is easy to see that a whole clause is involved:
But the whole clause is still involved in cases where other elements have been ellipsed:
Here the train to Bilbao for the late afternoon flight is an elliptical clause consisting of three explicit elements - Subject: the train + Adjunct: to Bilbao + Adjunct: for the late afternoon flight, with Finite/Predicator and Complement left out by ellipsis. The general prindple is that as long as only one element is involved, we can analyse the complexing at group/phrase rank, but as soon as more than one element is involved, we have to analyse the complexing at clause rank and posit ellipsis in one of the clauses.