specadd is a F90 module which does the following
module specadd
Read input sets
Check that they are spectral files
Create an output multiple spectrum file
If (useoldsumset) is true
copy oldsumset in output sumset
create those columns not present in oldsumset
else
create all necessary columns
endif
Insert n (n=numberOfSingleSpectra) new rows in sumset
For each of the n single spectra in sets
add single spectrum to sumset
End
end module specadd