Examples of the parameter space for two Gaussians combined to model asymmetric emission line profiles of the types and classes defined in this work (see Sect. 4.2). Lines encicle the region of possible values of the | ΔV | and I_s/I_d parameters resulting in an asymmetric profile of the classes a) A0, A1, and A2, b) B0, B1, and B2, and c) C0, C1, and C2 indicated by colors. Each plot includes the velocity dispersion ranges for the secondary (σ_s ~ [120 − 334] km s^-1) and dominant (σ_s ~ [90 − 154] km s^-1) components used to model the profiles.