High level summary of vertical interpolation approach?

[moptis]

Hello, not sure if this is the best place for this question, but I'm wondering if there is any documentation on the basic approach used to interpret WRF model level output to a given height. Is it linear? Exponential? Log pressure level? I'm trying to read through the wrf_vinterp.f90 source code but can't quite piece it together.

Thanks!