  In a market of deterministic cash flows, given as an additive, symmetric
relation of exchangeability on the finite signed Borel measures on the
non-negative real time axis, it is shown that the only arbitrage-free price
functional that fulfills some additional mild requirements is the integral of
the unit zero-coupon bond prices with respect to the payment measures. For
probability measures, this is a Choquet representation, where the Dirac
measures, as unit zero-coupon bonds, are the extreme points. Dropping one of
the requirements, the Lebesgue decomposition is used to construct
counterexamples, where the Choquet price formula does not hold despite of an
arbitrage-free market model. The concept is then extended to deterministic
streams of assets and currencies in general, yielding a valuation principle for
forward markets. Under mild assumptions, it is shown that a foreign cash flow's
worth in local currency is identical to the value of the cash flow in local
currency for which the Radon-Nikodym derivative with respect to the foreign
cash flow is the forward FX rate.
