GTC EMIR spectrum of J1714+4148 in the Hβ and [OIII] spectral region (black lines). The flux is in units of ×10⁻¹⁸ erg s⁻¹ cm⁻² Å⁻¹. Different fits (red lines) were attempted by applying a variety of kinematic constraints to [OIII] and/or Hβ (fits 2–7) or by leaving the kinematic parameters free (fit 1). For each fit, the constraints on the observed FWHM in Å are shown. It is also specified whether Hβ was forced to have the same redshift as [OIII]λ5007 (λ forced, fits 2 and 2b). The reduced chi-squared χ² are also shown, and the best-fit profiles are presented underneath each panel.