  It is proven that in indefinite metric quantum field theory there exists a
dense set of analytic vectors for the generator of the one parameter group of
x^0-x^1 velocity transformations. This makes it possible to define complex
velocity transformations also for the indefinite metric case. In combination
with the results of Bros -- Epstein -- Moschella, proving Bisognano--Wichmann
(BW) analyticity within the linear program, one then obtains a suitable
generalization of the BW theorem for local, relativistic quantum fields acting
on Krein spaces ("quantum fields with indefinite metric").
