  We consider transformations of the $2\times2$ propagator matrix in real-time
finite-temperature field theory, resulting in transformed $n$--point functions.
As special cases of such a transformation we examine the Keldysh basis, the
retarded/advanced $RA$ basis, and a Feynman-like $F\bar F$ basis, which differ
in this context as to how ``economically'' certain constraints on the original
propagator matrix elements are implemented. We also obtain the relation between
some of these real-time functions and certain analytic continuations of the
imaginary-time functions. Finally, we compare some aspects of these bases which
arise in practical calculations.
