Halliday & Matthiessen (2014: 514):
The projected clause here stands for a ‘wording’: that is, the phenomenon it represents is a lexicogrammatical one. Take for example ‘I’m not so sure,’ replied the Fat Controller. While the projecting clause replied the Fat Controller represents an ordinary phenomenon of experience, the projected clause I’m not so sure represents a second-order phenomenon, something that is itself a representation. We will refer to this as a ‘metaphenomenon’. If we want to argue, the issue is not ‘is he or is he not, so sure?’ – that is a separate question; it is ‘did he, or did he not, say these words?’ The total structure, therefore, is that of a paratactic clause complex in which the logical-semantic relationship is one of projection; the projecting clause is a verbal process, and the projected clause has the status of a wording.