The removal of oxygen from YBa2Cu3O7-x has a profound impact on variou
s properties of this compound. The model of induced two gap supercondu
ctivity that we developed previously allows us to describe these prope
rties. For example, for compositions between 0 < x <0.15, the energy g
ap on the chains changes drastically, and in fact. becomes gapless. Ho
wever, T(c) remains relatively constant, because it is determined most
ly by the properties of the planes. We find from specific heat measure
ments that the electron-phonon coupling on the planes is sufficient to
account for the high T(c) in YBa2Cu3O7-x. Furthermore we can explain
the unusual doping dependence of the isotope shift to effects of non-a
diabaticity of oxygen motion in these compounds.