The second question that arises is

The second question that arises is how clause combination should be restricted. We have indentified stylistic and discourse constraints. The stylistic constraints are constraints against the sentence becoming too long (an upper bound on the number of clauses that can be combined into one sentence), and a constraint on recursive embedding of relative clauses. Discourse onstraints are imposed by the structure of the text: clauses belonging to conceptually distinct text units should not be combined. The text planner can send a special message, called conceptual-break, to the sentence planner. It signals the beginning of a new textual unit. These special messages are triggered by appropriate indications in the DICKENS specifcation of the DCK.