The simplest way to run Scientific Analysis for a specific instrument is to set the parameters you are interested in, and to run the corresponding main script. There are several ways of entering the parameters: you can either input them from the command line, or use a Graphical User Interface (GUI), which is launched automatically when you run the script. From the command line you should enter those parameters that are not defined as hidden in the parameter file (see below), and those hidden parameters that you want to change. With a GUI you can see all parameters selecting the option ``Show hidden parameters''. The place from where the parameter files are taken is defined by the value of the PFILES environment. It has the following structure:
echo $PFILES local/directories/pfiles;system/directories/pfiles:system/directories/pfiles
First the parameter file is looked for in the local directories (from left to right), and then, if not found, in the system directories. In the later case the parameter file is copied to the local directory. If you have changed the OSA version on your computer, you should delete all parameter files from your local pfiles directory to avoid inconsistency of the parameters.