"save" writes selected atoms to a file. The file format is
autodetected if the extesion is ".pdb", ".pse", ".mol", ".mmod", or
Note that if the file extension ends in ".pse" (PyMOL Session), the
complete PyMOL state is always saved to the file (the selection and
state parameters are thus ignored).
save file [,(selection) [,state [,format]] ]
cmd.save(file, selection, state, format)
When saving a session file, then "state" has no effect.
When state = 0 (default), only the current state is written.
When state = -1, then a multi-state output file is written (PDB only).
Cmd load, Cmd get_model