How is compliance tensor calculated in comsol for isotropic materials?

I have been working on a piezoelectric cantilever.
At some point I wanted to see what would be the difference if the piezoelectric material was considered isotropic regarding his compliance matrix (strain-charge form in the material definition).
What surprises me is that for isotropic materials, comsol does not take into account, nor does it ask, for Poisson's ration, Shear moduli or anything else.
If I understood correctly, isotropic material do have non diagonal terms in their compliance matrix and they depend on Poisson's ratio.
How come comsol doesn't need any of theses terms ?

Regards,
Pierre