Theme: first constituent in the clause
Marked Theme: a constituent is moved to the front of the clause (thematized)
Absolute Theme: not participants or circumstances in clauses, with as for or concerning etc
As for the salad, I'd just prefer to have lots of olives, tomato and feta.
Picked up Theme: Jean, she hasn't got a key anymore.
Nonexperiential Theme
Interpersonal Theme: in my opinion, frankly, fortunately
Textual Theme: however