This part is divided into 80 sections, each devoted to one element. The elements are ordered by their English names. Cross references between names, formulae and atomic numbers are given in the appendices (part four, tables 2–4).

For the description of the behavior of each element we have kept a constant order, which is as follows.

1. 1 The formula, the English name and the atomic number.

2. 2 A short history of the discovery of the element and an explanation of its name and/or abbreviation. If not indicated otherwise, these data are taken from Elmsley (1989).

3. 3 The ionization energies, in electron-volts (eV), rounded off to the nearest tenth of an electron-volt. The data were taken from Samsonov (1968) and Elmsley (1989). We have only quoted those ionization stages that are observed in stars, plus the next one.

4. 4 We then start a description of the behavior of the lines of each ionization stage (i.e. each species), beginning with the neutral lines. In order to be as precise as possible, we have given the behavior of the equivalent widths of one or more absorption lines with spectral type. Wavelengths and equivalent widths are given in ångström units (1 Å=10−8 cm=0.1 nm), except when stated otherwise. These values are listed in tables and, if sufficient values are available, plotted in figures. The figures provide only smoothed curves, based upon the values listed in the tables. All figures give the spectral types on the abscissae and the equivalent width (in ångström units) on the ordinates.

If data exist in the literature, separate curves have been plotted for dwarfs and supergiants and sometimes also for giants.