Position P2 is from Simon Dik's book, The Theory of Functional Grammar: Part I: The Structure of the Clause (FGS 9; Dordrecht; Providence, R.I.: Foris, 1989), a 400+ page book that I've got to read...so little time, so many books : )
Here's what it looks like graphically, so you get an idea of what he's talking about. X is the normal spit for stuff that isn't "marked":
(P1) (P2) VERB X, where
::Position P1: may contain one or more established clause component;
::Position P2: may contain a nonestablished clause component,
::X represents the other nonverbal components of the clause.
Note: The parentheses around P1 and P2 means that they are optional.
Makes sense, doesn't it, especially for VSO languages such as Greek and Hebrew.