The field widths in line 3 are used to read and write files in the fixed field-width .PRN format. The rest of this file consists of data on the oxides. Molecular weight of oxide. Number of atoms in oxide formula unit. Valence of atom.
Anions have negative valence.
Several .REF files are supplied, which differ in the definition of the sample information fields. Mineral name, abbreviated. Numeric field to identify the analysis, e.g. a spot number such as 2.3, signifying grain 2, analysis spot no 3. M9BASE.REF is similar to this, but adapted for data acquired on the Oxford Microscan 9 electron microprobe. Two additional fields are for the stage X and Y coordinates.