The loadings plot shows the contribution of spectral regions to the
variation of a factor. Their values range between 1 and -1 and they directly
reflect the correlation of a particular spectral region to the factor.
The closer a spectral region in this plot is located at 1 or -1, the more
this spectral region is explained by this factor.
By default the loadings plot is displayed together with the plot configuration
window on the right side of the tab. The configuration window may be used
to customize the loadings plot.