Examples of the different spectral shape categories (Sect. 4.1), except the ‘no-peak’ category (see Appendix D). First row: spectra of single-peak galaxies. Second and third rows: spectra from sources belonging to the double-peak category, red and blue dominated spectra, respectively. Last row: spectra showing triple-peak Lyα lines. We note that the y-axis shows the flux normalized to the maximum of each line.