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

 EXS    Exit the program as with EX and print elapsed CPU time

 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 gmagblocks4.sta 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, and the third column
        the uncertainty (error bar).  If the first character in the line
        is #, the line is not read.

 SLP    Generate and print layer profile.  Append A, B, C, or D to 
        generate scattering density for the specified cross-section.
        Append O to generate separate magnetic and chemical profiles
        before their integration into a common profile.  SLP saves
        into file entered by OF (or IF if not yet given) with extension
        .proC where C is n, m, t, a, b, c, d, N or M.

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

 SV     Save values in Q4X and YFIT to file entered with OF with the
        extension .genC where C is a, b, c or d.

 SVA    Save values in Q4X and YFITA to file entered with OF with the
        extension .genC where C is a, b, c or d.