Initial position is thematic; and the natural theme of a process or participant is its relation to the here-&-now. Final position is informative; and the newsworthy component of a process or participant is some aspect of its lexical content. So the structure of groups recapitulates, in the fixed ordering of their elements, the meaning that is incorporated as choice in the message structure of the clause.
Friday, 12 April 2019
Halliday & Matthiessen (2014: 397):