  On 3rd September 2015, the Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP) successfully measured the linear polarization produced by scattering
processes in the hydrogen Lyman-$\alpha$ line of the solar disk radiation,
revealing conspicuous spatial variations in the $Q/I$ and $U/I$ signals. Via
the Hanle effect the line-center $Q/I$ and $U/I$ amplitudes encode information
on the magnetic field of the chromosphere-corona transition region (TR), but
they are also sensitive to the three-dimensional structure of this corrugated
interface region. With the help of a simple line formation model, here we
propose a statistical inference method for interpreting the Lyman-$\alpha$
line-center polarization observed by CLASP.
