!Options::::::
Options are variables set by the user to control the state or flow of SPEX.  They affect
the data selection, appearance of the plots in the TIME and SPECTRAL graphics windows, the
fitting data selection and other functions.  Most are modified by direct user action
although some may be modified by the action of (W)SPEX.

!!APAR           
	Model Fit Initial Parameters.  Float array
!!BACK_ORDER  
	Background is fit over selected time ranges in 5 energy bands 
	using a polynomial order BACK_ORDER
!!DATA_TIPE
	Specifies the kind of data to use, e.g. BATSE SHERS refers to
	the high energy resolution data from the SPEC detectors
	on BATSE
!!DET_ID
	Detector ID, for BATSE LAD or SPEC they run from 0-7 
!!DET_TYPE   
	Detector type used internally to help create response functions.
!!DFLTS_FILE
	File with defaults for these options. Default name is 'spex_dflts.dat'
!!ENERGY_BANDS
	Energy bands (keV) used for multiple light-curve display. A fltarr(8), grouped by twos.
	Used by GRAPH command in SPEX or the button
	'TIME HISTORY.PLOT LIGHT CURVE (READ).MULTI-TRACE'.   
!!EPLOTS 
	Logical.  If set, then display error bars in GRAPH command.
!!ERANGE 
	         FLOAT     = Array(2)
	Energy interval used to select channels for fitting.
!!FLARE  
	BATSE or HXRBS archive flare number.  Database must be accessible.
!!FREE   
        INT       = Array(6)
	Logical array.  Set to 0 or 1 corresponding APAR parameter in the fitting
	model, F_MODEL, is fixed(0) or free(1).  Number of elements depends on the model.
!!F_MODEL 
	Name of function used in modlel fitting.  Normal default is 'f_vth_bpow'
	which is a thermal + double power-law form.  There are 6 parameters for this function:
	0. The emission measure of the thermal in units of 1e49 cm^(-3) from the Sun.
	1. The temperature of the thermal in keV.
	2. The normalization of the first power-law at 50 keV in photons/cm^2/s/keV.
	3. The spectral index of the power-law at energies below the break.
	4. The break energy in keV.
	5.  The spectral index of the power-law at energies above the break.
	
!!HIGH_DRM
        INT       =        0
	Logical.  If set, then the high energy versions of the response matrices are used.
!!IAVG   
         INT       =        1
	Interval grouping parameter.  Used under SELECT_INTERVAL.  IAVG consecutive intervals
	are grouped together when using REGULAR interval selection mode.
!!IEAVG 
        INT       =        1
	Spectral interval averaging parameter.  For display purposes only at present.  Used
	under SPEC_BANDS command and 'SPECTRAL FITS.SPEC PLOT BINNNG.SELECT' button.
!!IFIRST  
        INT       =        0
	First accumulation interval to use for fitting and PHOTON_SPECTRUM or COUNT_SPECTRUM
	display.
!!ILAST  
	INT       =        3
	Last accumulation interval to use for fitting and PHOTON_SPECTRUM or COUNT_SPECTRUM
	display.
!!ITER    
	INT       =        4
	Number of outside loops in Curvefit where conversion factors are recomputed.
!!NITER  
	INT       =        5
	Number of loop within Curvefit.
!!QUIET  
	INT       =        0
	Logical, if set, it reduces the reporting during fitting.
!!RANGE_HI 
	FLOAT     = Array(6)
	Upper limits to fitting parameters inside Curvefit.
	Same as RANGE(*,1).
!!RANGE_LO        
	FLOAT     = Array(6)
	Lower limits to fitting parameters inside Curvefit.
	Same as RANGE(*,0).
!!SCALE_BANDS     
	FLOAT     = Array(4)
	Multiplicative factors applied to light curve bands in GRAPH or the button
	'TIME HISTORY.PLOT LIGHT CURVE (READ).MULTI-TRACE'.
!!SPXRANGE        
	FLOAT     = Array(2)
	If non-zero, this is the xrange used in spectral plotting.
!!SPYRANGE
	FLOAT     = Array(2)
	If non-zero, this is the yrange used in spectral plotting.
!!SUMFIT 
        INT       =        0
	If not set, then the initial fit parameters for interval i are taken from the 
	previous interval, apar_arr(*,i-1).  If set, then the initial fit
	parameters are taken from the previous fit to interval i
	in apar_last(*,i).
!!T_HIST_MODE
	STRING    = 'FLUX'
	Sets the Y-axis units for time-history plots.  Either:
	FLUX for counts/s/cm2/keV
	or 
	COUNTS for counts/s
!!TEST_DRM
	INT       =        2
	Set this to 1 or 2 to calculate the development detector response matrix (DRM).
!!UNCERT          
	FLOAT     =     0.0500000
	Minimum fractional uncertainty on count rate data.  Added in quadrature to 
	statistical uncertainties.
!!UTE    
        STRING   e.g. '91/07/24, 23:05:16.141'
	Timerange upper bound.  Set by Zoom command.
!!UTS             
	STRING   e.g. '91/07/24, 23:04:06.695'
	Timerange lower bound.  Set by Zoom command.
!!WUSE            
	LONG Array
	Indices of data bins along energy axis to be used in fitting.
	These are set through the ERANGE option,  the ENRANGE command, or the
	'SPECTRAL FITS.FIT.SELECT ENERGY RANGE' button.
!Variables::::::
These arrays are created as data is found and read, plotted as light curves, plotted as
spectra and fit to standard models.

!!APAR_ARR        FLOAT     = Array(6, 4)
	Fit Model parameters for each interval.
!!APAR_LAST       FLOAT     = Array(6, 4)
	Fit Model parameters for last fit to each interval.
!!APAR_SIGMA      FLOAT     = Array(6, 4)
	Curvefit uncertainties on APAR_LAST
!!AREA            FLOAT     =       127.000
	Geometric area of detector for normal incidence, cm2
!!BACK            FLOAT     = Array(256, 131)
	Generated background rate for each channel, time bin.  Same units as FLUX
!!BACKI           FLOAT     = Array(256, 4)
	Background for accumulation interval.
!!BACK_SIGMA      FLOAT     = Array(256)
	Uncertainty on BACK, from poly_fit.
!!BURST           INT       =      574
	BATSE burst number
!!CHI             FLOAT     = Array(1, 4)
	Reduced chi square for each accumulation interval	
!!CONVI      FLOAT     = Array(256)
	Conversion factor for the last displayed photon spectrum.  Defined as the
	count rate spectrum divided by the photon spectrum defined at the energies
	given by the vector EMEDGE, which is defined to be the arithmetic means
	of the channel edges.
!!COSINE          FLOAT     =      0.746035
	Cosine of the angle between the detector normal and the photon source.
!!COUNT_2_FLUX    FLOAT     = Array(256) 
	Conversion from count rate to count flux, channel energy width x area.
!!DRM             FLOAT     = Array(256, 100)
	Detector response matrix, output channels x input energies.  Defined as the
	counts/cm2/keV per incident photon/cm2
!!EBACK           FLOAT     = Array(256, 131)
	Uncertainties on BACK.
!!EBACKI          FLOAT     = Array(256, 4)
	Uncertainties on BACKI.
!!EDGES           FLOAT     = Array(2, 256)
	Detector energy-loss channel edges.
!!EFLUX           FLOAT     = Array(256, 131)
	Gaussian uncertainties on FLUX
!!EM_IN           FLOAT     = Array(100)
	Arithmetic mean of E_IN
!!EOBSI           FLOAT     = Array(256, 4)
	Uncertainties on OBSI.
!!EPIVOT (FUNCTION_COM)FLOAT     =       50.0000
	Pivot energy in keV.  Used as normalization energy for power-law functions.
!!E_IN            FLOAT     = Array(2, 100)
	Incident energies defined for DRM.
!!FILES           STRING    = Array(2)
	Datafiles selected under TIME_HISTORY command.
!!FLUX            FLOAT     = Array(256, 131)
	Observed count rate, channels by intervals, in counts/s/keV/cm2,
	no background subtracted
!!IEGROUP         UNDEFINED = <Undefined>
	Channel number boundaries of spectral channels grouped together.
!!ISELECT         LONG      = Array(2, 4)
	Index of interval boundaries (referenced to FLUX) of accumulation intervals.
	The ith interval starts at the leading edge of ISELECT(0,i) and ends at the leading
	edge of ISELECT(1,i).
!!LIVE            FLOAT     = Array(256,4)
	Live time in seconds of each channel in every accumulation interval.
!!LTIME           FLOAT     = Array(256,131)
	Live time in seconds of each FLUX observation channel for every time bin.
!!NBIN            LONG      =          131
	Number of time intervals in FLUX.
!!NCHAN           LONG      =          256
	Number of spectral intervals in FLUX.
!!OBSI            FLOAT     = Array(256, 4)
	Source flux in accumulation interval I.
!!RANGE           FLOAT     = Array(6, 2)
	High and low boundaries for APAR values during fitting.
!!RATE            FLOAT     = Array(256, 131)
	Background subtracted count rate, same units as FLUX and BACK
!!TB              FLOAT     = Array(4)
	Boundaries of background intervals.
!!UT              DOUBLE    = Array(2, 131)
	Time boundaries for bins in FLUX.  Expressed in seconds from
	time given by ATIME( getutbase(0))
!!UTM             DOUBLE    = Array(131)
	Midpoints of UT.
!!WEDGE           FLOAT     = Array(256)
	Widths (keV) of output energy bins, EDGES.
!!WUSE            LONG      = Array(87)
	Indices of energy bins used in fitting.
!!W_IN            FLOAT     = Array(100)
	Widths (keV) of input energy bins, E_IN.
!!XSELECT         DOUBLE    = Array(2, 4)
	Time boundaries on accumulation intervals referenced to the same base
	as UT.
!Commands::::::
These commands are issued at the SPEX prompt to initiate data selection, time and
energy selection, fitting, and plotting.

!!ACCUM 
Integrate the spectral data in FLUX over the selected
time intervals.	
!!TIME_HISTORY 
Read the data files for the chosen event into FLUX
and UT and plot the light curve in the time history window.	
!!COUNT_SPECTRUM
Plot the count rate spectrum for the current interval, IFIRST, and overlay the
calculated count rate from the given by F_MODEL and the current fit parameters
for the interval in APAR, APAR_ARR, or APAR_LAST.	
!!PHOTON_SPECTRUM 
Plot the photon spectrum for the current interval, IFIRST, and overlay the
calculated photon spectrum from the given by F_MODEL and the current fit
parameters for the interval in APAR, APAR_ARR, or APAR_LAST.  The opportunity
is also presented to graphically select the model parameters.	
!!LIST 
Print a list of the control parameters and their values as well as the 
commands to the screen.	
!!EXIT 
Exit the SPEX procedure and return to IDL at the main program level.	
!!FITTING 
After the data is read by TIME_HISTORY, the DRM created under
the DRM menu, the intervals selected using SELECT_INTERVAL, the model
parameters initialized using PHOTON_SPECTRUM, the free parameters determined by
the value of the FREE array, the allowed energy range selected by the value of
ERANGE, the intervals are fit using a modified curvefit running from IFIRST to
ILAST.	
!!EXECUTE 	
Prompts for an IDL command line to be input for the IDL EXECUTE function.	
!!STOP 
IDL STOP.  Resume by entering .c at the IDL prompt.	
!!ZOOM 
Interactive selection of a reduced xrange.  Restore full scale with
CLEAR_UT.
!!DISPLAY_INTERVAL 
In the time history window, which must be the active window, overlay lines at 
the boundaries of the accumulation intervals.	
!!SELECT_INTERVAL 
In the time history window, which must be the active window,
interactively select the time  intervals for integration prior to FITTING. 
Also, the time intervals may be input directly  into the array, XSELECT =
fltarr(2,N) where the times are referenced to the same base as the data
intervals in UT and each interval is specified by its boundaries.	
!!BACKGROUND_INTERVAL 
In the time history window, which must be the active window, interactively
select the time  intervals for background accumulation.  The default background
model is a linear interpolation in time over the data points in two 
selected background intervals.  Experienced users may change the order
of the polynomial fit used by changing the parameter BACK_ORDER from its
default value of 1.
!!INITIALIZE
Restore some of the original defaults. 
!!GRAPH
Plot light curves in the time history window.  Light curves are integrated in
energy over the ranges specified by ENERGY_BANDS or CHANMASK and may
be rescaled by changing SCALE_BANDS.
!!DRM
Enter the DRM menu to READ or BUILD load the detector response matrix, DRM.
!!READ_DRM
Read the DRM files specified by DFILE for the direct response matrix and
SCATTERFILE for the response matrix due to scattering off the earth.  The
response matrix is interpolated to fine bins and then integrated over the
output bin energies for the specific data type on the date of the event.
!!BUILD_DRM
Create the DRM direct detector response matrix, DRM, by interpolating in 
the source aspect angle over a stored set of response matrices.  The
response matrix is then interpolated to fine bins and integrated over the
output bin energies for the specific data type on the date of the event.
!!TOP
Return to the main SPEX menu from a branch menu.
!!STEPS_HELP
Describes the step-by-step procedure for processing spectra through
the SPEX menu.
!!SUMMARY
Enter the SUMMARY menu to save and restore processed spectra and fit
parameters.  
!!ERASE
Clears a Tektronix graphics page.
!!TEK
Sets the graphic display to Tektronix.
!!FIND_FILES
Find the filenames or verify the filenames specified under the parameters
_1FILE and _2FILE.  Mostly unneeded using automatic file finding defaults
with the filename parameters left blank.
!!ENRANGE
With the SPECTRAL WINDOW active (last plotted to), graphically select 
the energy limits on the spectra to be fit.
!!CH_BANDS
With the SPECTRAL WINDOW active (last plotted to), graphically select 
the four ranges in the ENERGY_BANDS parameter.
!!SPEC_BANDS
With the SPECTRAL WINDOW active (last plotted to), graphically select 
the groups of channels to be summed together for display.  Does not affect
binning for fitting which uses individual channels within the limits
specified by ERANGE.
!!NOSPEC_BANDS
Resets the grouping of SPEC_BANDS to single channels without any grouping.
!!BSPECTRUM
Displays the background count rate energy spectrum.
!!RESTORE_DFLTS
Reads the parameter values saved in the file given by the parameter,
DFLTS_FILE.
!!SAVE_DFLTS
Saves the parameter values saved in the file given by the parameter,
DFLTS_FILE.  Use to save the setup for a particular data set.  The file
will be named in a systematic fashion if DFLTS_FILE is set to AUTO.
!!CLEAR_UT
Resets the timerange in the TIME HISTORY WINDOW to the limits of the vector
UT, i.e. to the extent of the time interval covered by the current data set
input through TIME_HISTORY.
!!KLEANPLOT
Runs the routine CLEANPLOT which resets the system plotting structures
to their defaults.
!!FORCE_APAR
Sets the fitting parameters in each interval in the arrays APAR_ARR and
APAR_LAST to the values in APAR.  APAR_ARR and APAR_LAST are dimensioned
fltarr( npar, nint) where npar is the number of parameters in the fitting
model (see F_MODEL) and nint is the number of fitting time intervals (see
the parameters XSELECT and WINT).
!!COMMENTS
Print recent messages about the status of SPEX including problem reports
and new features.
!!T_HIST_MODE
Set the display mode for the TIME_HISTORY and GRAPH commands to COUNTS or
FLUX to see the light curves in units of COUNTS/S or COUNTS/S/KEV/CM2,
respectively.