  The interpretation of the main sequence of quasars has become a frontier
subject in the last years. The consider the effect of a highly flattened,
axially symmetric geometry for the broad-line region (BLR) on the parameters
related to the distribution of quasars along their Main Sequence. We utilize
the photoionization code CLOUDY to model the BLR, assuming `un-constant' virial
factor with a strong dependence on the viewing angle. We show the preliminary
results of the analysis to highlight the co-dependence of the Eigenvector 1
parameter, R$_{\mathrm{FeII}}$ on the broad H$\beta$ FWHM (i.e. the line
dispersion) and the inclination angle ($\theta$), assuming fixed values for the
Eddington ratio ($\mathrm{L_{bol}}/\mathrm{L_{Edd}}$), black hole mass
($\mathrm{M_{BH}}$) and spectral energy distribution (SED) shape. We consider
four cases with changing cloud density (n$\rm{_{H}}$) and composition.
Understanding the FeII emitting region is crucial as this knowledge can be
extended to the use of quasars as distance indicators for Cosmology.
