The data file, os.fil, tells OS
1. the name of the clean PDB file
2. the range of residues to calculate the occluded surface for (all atoms are considering as potential occluding atoms, but the occluded surface is only calculated for those given in the range)
3. whether or not to create a file for display of the extended rays using MidasPlus (This option should be used for only a few residues at most - Midas crashes if you try to draw too many rays but the exact limit has not been determined)
The format of os.fil is as follows;
filename.pdb 2 167 n
An example to display the rays as in the lower half of the figure is as follows:
1stn.pdb 23 23 y
How to display the rays using MidasPlus is described here.
