The spi_science_analysis calls a number of individual programs and feed them with the relevant parameters with a certain logic. Let us take a concrete example, the program spiros, for the sake of clarity. The spiros parameters are listed in spiros.par (found at the $PFILES location. We have selected the most important spiros parameters when building the spi_science_analysis script, and these parameters are named spiros_''parameter's name'' in spi_science_analysis.par.
For example, ``nofsources'' from spiros.par becomes ``spiros_nofsources'' in spi_science_analysis.par. However, the spiros parameter ``kofsources'' from spiros.par is not in spi_science_analysis.par, because we decided it was not a parameter user should ``normally'' change. Remember that users can only directly access the parameters of spi_science_analysis.par, either from the GUI or from the command line.
In the spi_science_analysis code, all parameters are first specified (i.e., hard coded), and both ``nofsources'' and ``kofsources'' get default values at this stage. After that the script copies from the spi_science_analysis.par all ``spiros_...'' parameters, and supersede the default values of these parameters. In this way, the value of ``spiros_nofsources'' replaces the default value of ``nofsources''. However, the default value of ``kofsources'' (Kind OF SOURCES = POINT) cannot be changed as ``spiros_kofsources'' is missing in spi_science_analysis.par. A nice feature, however, is that it can easily be added.
Take your favorite editor, copy the ``kofsources'' line from spiros.par into the spi_science_analysis.par and add ``spiros_'' before ``kofsources''. Save the spi_science_analysis.par and launch the GUI (make sure the spi_science_analysis.par edited is at the right $PFILES location). The parameter now appears at the bottom of the main GUI (or at the bottom of the ``Hidden'' GUI if it is a hidden parameter). The GUI does not look very nice, but you can now modify the value of ``spiros_kofsources'', and it will be transmitted to spiros as ``kofsources''. You can also add ``spiros_kofsources'' on a command-line run.
After your run, you can check the actual value of ``kofsources'' in the spiros logfile.