EX     Exit the program and save parameters and constraints to file entered
        using PF command.

 QU     Exit without saving changes to parameter file entered with PF.

 !      Spawn a command.  Enter the command at the prompt.

 !!     Spawn a subshell.

 CD     Change current directory.  Tilde (~) expansion is performed.

 PWD    Print current directory.

 IF     Enter name of input file.

 OF     Enter output file name.

 PF     Enter parameter file name.  Default is taken from commandline
        argument.  Default is mlayer.staj if none given.

 LP     Load parameters from file entered using PF command without the
        constraints from that file.  This command resets the uncertainties.

 LPC    Load parameters from file entered using PF command and use the
        constraints from that file (automaticallly done when program runs).
        This command resets the uncertainties.

 SP     Save parameters to parameter file entered with PF.

 GD     Get data from filename entered using IF command.  The data is
        assumed to be in three-column format with the first column being
        the momentum transfer (Q=4 PI sin THETA/LAMBDA), the second
        column either the logarithm of the counts or the spin asymmetry,
        and the third column the uncertainty (error bar).  If the first
        character in the line is #, the line is not read.

 SA     Generate and print unconvolved complex amplitude of reflectivity.
        The data are saved into file entered by OF.

 SLP
 SSP    Generate and print layer profile.  The data are saved into file
        entered by OF (or IF if not yet given) with extension .pro
        SLP saves the critical angle in histogram form.  SSP saves scaled
        critical angle and absorption in table form.

 SRF    Save fit to reflectivity in file name entered in OF with
        extensinon .fit.  Written in two-column format:  first column is
        Q=4 PI sin THETA/LAMBDA, second is fit.

 SRSF   Save fit to spin asymmetry in file name entered in OF with
        extension .fit.  Written in two-column format:  first column is
        Q=4 PI sin THETA/LAMBDA, second is fit.

 SV     Save values in XTEMP and YTEMP to file entered with OF.