reflpol is implemented as a GUI layer on top of the underlying gj2 program. For the most part you will never need to access gj2 directly, but there are some features which are not yet implemented in the GUI.
In particular you may need:
ulc - unload constraints
lc - load constraints
ps abcd - use all four polarization states when fitting.
sl A B N y - repeat layers A to B N times, erasing B+1 to B+N*(B-A).
ql "lo hi" - set Q range for simulation from lo to hi.
np n - use n points in Q range for simulation
srf - save log(R) to file (use 'of file' to set file name)
slp - save layer profile
You must be sure to use the correct number of parameters for the command, or you will need to exit and restart the program. In practice this means you will need to try them directly in the underlying program before you can use them from the GUI.
The attached pages list all the gj2 commands for completeness, but you will not need most of them, and some of them will cause the link between the GUI and gj2 to fail, so save your state before continuing!
gj2 parameters
gj2 layers
gj2 fit
gj2 io
gj2 display
gj2 plot
Don't try running the movie commands directly, because the command window will timeout before the movie is complete. The Tcl console allows you to program your own movies.