UPDATE...RETURNING col INTO var - what is returned?

Hi all,
I just got quite confused on the exact semantics
of "RETURNING expressions INTO target" with an update statement.

And while trying to resolve failed to find an answer in the  docs.

Question was whether - in case "expression" is involving a column that is assigned by the update itself -
the value returned is based on the "old" value or the "new" value".

While I'm no back to assuming is has to be the "old" one,
I did not find a reference to that fact with the docs.

Where should I have looked?
Or is it actually missing?
Then, could one add this, e.g. to the description of RETURNING .. INTO (Executing a query with a single row result)
just for clarification, to dispel doubts.


Thanks
Rainer