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Fig. 1


Wavelength intervals used by the eleven different groups analysing the optical spectra. See Sects. 3.1 to 3.5. For the M3b analysis (Sect. 3.1.3), discontinuous wavelength regions totaling  ~435 Å were used. The M6, A1, and A4 groups (Sects., and 3.2.4) used spectrum synthesis for individual spectral lines distributed over the indicated regions. The A2 and A5 groups (Sects. 3.2.2, and 3.2.5) used equivalent widths for individual spectral lines.

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