Having a set of reliable parameters characterizing a given spectral line is of pivotal importance for the understanding of the physical conditions in the region where the line is formed. The following parameters were computed for the emission lines presented in this work: line to continuum ratio at emission line peak and velocity at which it occurs (vpeak ), full width at half maximum (FWHM), half width at zero intensity (HWZI), maximum velocities observed in the line wings (vblue and vred ), equivalent width (EW) and Asymmetry Factor (Af). The HWZI was computed from vblue and vred which were calculated at the 2% level of the the peak intensity. The name 'HWZI' is therefore slightly misleading since, in reality, the width was not computed at zero intensity. However, 'HWZI' will be used throughout this work. The Af is defined as the ratio of the line equivalent width blueward of the zero velocity to the line equivalent width redward of the zero velocity.
A method devised to measure these parameters and to estimate the associated uncertainties is described in the following section.