  Beginning with the pioneering work of Regge and Wheeler (Phys. Rev. 108,
1957), there have been many studies of perturbations away from the
Schwarzschild spacetime background. In particular several authors (e.g.
Moncrief, Ann. Phys 88, 1974) have investigated gauge invariant quantities of
the Regge-Wheeler (RW) gauge. Steven Detweiler also investigated perturbations
of Schwarzschild in his own gauge, which he denoted the "easy (EZ) gauge", and
which he was in the process of adapting for use in the second-order self-force
problem. We present here a compilation of some of his working results, arising
from notes for which there seems to have been no manuscript in preparation. In
particular, we list the gauge invariant quantities used by Detweiler, as well
as explain the process by which he found them.
