Halliday & Matthiessen (1999: 109, 110):
We have seen that the content plane is stratified into two levels — semantics (the level of meanings) and lexicogrammar (the level of wordings). Consequently, we would expect projections to be located at either or both of these levels, and this is indeed what happens: a projected figure is either a meaning or a wording: see Figure 3-4.
