Notes:
(1) The input model may contain more than one model (i.e. it may be
an entire grid of models). Spectrum will cycle through this grid NMOD times,
omitting NSKIP-1 models from the
input for each model treated. However, the input data following MODE
must be repeated NMOD times in order to obtain equivalent results for each
model in the grid. WARNING CSJ has never used multiple model inputs and
regards this feature as obsolescent.
(2) The elemental abundance is entered as a number fraction, either
as a logarithm normalized such that [H] = 12.00 in hydrogen-normal stars,
or as a fraction such that n_H = 1.0 in hydrogen-normal stars (an additional
note on what happens for stars in which hydrogen is not normal will follow).
(3) If the abundance is entered as a negative number, it is assumed
to be the line equivalent width. Spectrum will apply a Newton-Raphson iteration
to derive the elemental abundance which will reproduce this equivalent
width for the current model atmosphere.
(4) SPECTRUM searches the linelist for the line belonging to species
Z which lies closest to and within WTOL of lambda. It computes the total
equivalent width due to this line and to any blending line belonging to
the same 'multiplet' that lies within WTOL of the principle line. Normally
WTOL=1.0 Angstrom, but if Z is negative, then WTOL=0.1 Angstrom.