# Component/    parameter   constraint	Comment
# operation	(see below)   range

    3              n        0.7 to 5    # Soft constraint: Constrains the 
					# sersic index n to within
				        # ABSOLUTE values from 0.7 to 5.

    2	  	   x	     -1  0.5	# Soft constraint: Constrains 
					# x-position of component
					# 2 to within +0.5 and -1 of the
					# INPUT value.

    2	  	   x	     -1 in 0.5	# Alternative version of above.

    1	  	   x	     -2.0 ref 2.0   # Soft constraint: Constrains
					   # x-position of component
					   # 1 to within +2.0 and -2.0 of the
					   # value at the REFERENCE wavelength.

    1	  	   re	     factor 3.0	   # Soft constraint: Constrains the 
					   # Re to be within a factor of 3 of the
					   # input value (new in GALFITM)

    3              n_1        -10 to 10    # Soft constraint: Constrains the first
				  	   # order (linear) Chebyshev coefficient
					   # describing the dependence of component
					   # three's sersic index n on wavelength
					   # to within values from -10 to 10.

    2	  	   re_B	     -1  0.5	# Soft constraint: Constrains the B-band
    		   	     	 	# effective radius of component two to be
					# within +0.5 and -1 of the input value.

    3-7		   mag	     -0.5 3	# Soft coupling-constraint:  The magnitude 
					# of component 7 is constrained to 
					# be WITHIN a range -0.5 mag brighter 
					# than component 3, 3 magnitudes 
					# fainter.

    3/5		   re	       1  3	# Soft constraint:  Couples components 
					# 3 and 5 Re or Rs ratio to be greater 
					# than 1, but less than 3. 

  3_2_1_9          mag        offset	# Hard coupling-constraint: Constrains
					# the magnitude of components 3, 2,
					# 1, and 9 to maintain RELATIVE offsets as
					# defined by the initial parameter file,
					# provided no wavelength dependence of x
					# is allowed.
  
  1_5_3_2	   re	      ratio     # Hard coupling-constraint: similar to above
					# except constrain the Re parameters 
					# by their ratio, as defined by the
					# initial parameter file, provided no
					# wavelength dependence of x is allowed.

  1_2_3  	   x_0	      offset    # Hard coupling-constraint: The x-position
  1_2_3  	   x_1	      offset    # of components 1, 2 and 3 are constrained
  1_2_3  	   x_2	      offset    # to maintain their initial offsets, in the
					# case where a quadratic dependence on
					# wavelength is permitted.
					

# Note on parameter column:
#   The parameter name options are x, y, mag, re (or rs -- it doesn't matter),
#   n, alpha, beta, gamma, pa, q, c, f1a (Fourier amplitude), f1p (Fourier
#   phase angle), f2a, f2p, r5 (coordinate rotation), etc., .  Or 
#   alternatively, one can specify the parameter number instead (for the
#   classical parameters only) corresponding to the same numbers in the 
#   galfit input file.

# Notes for multi-band data:

# The format for specifying constraints in GALFITM is essentially the
# same as for GALFIT3, with a few additions and caveats, as described
# below.

# Note that the way in which constraints are applied has changed in
# GALFITM, so single-band fits with GALFITM will sometimes give
# different results to GALFIT3.  As there are hard-coded constraints
# (e.g. re > 0), differences can occur even without user-specified
# constraints.

# Constraints are applied in order.  However (to avoid potential
# confusion) hard coupled-component constraints are always applied
# last.

# Fourier and rotational transforms are not supported with multi-band data.

# 

# Soft single-component constraints: 
#   These constrain a single parameter to lie between two limiting
#   values.  Unadorned parameter names imply constraints which apply
#   across all the input wavelength bands.  However, if desired, these
#   constraints can be applied to specific bands or Chebyshev
#   coefficients (see below).
#   For convenience, GALFIM introduces an option for constraining a
#   parameter value to be within some factor of the input value.

# Soft coupled-components constraints:
#   These can only be specified in terms of Chebyshev coefficients
#   (see below), and not in terms of actual band values.  Enabling
#   this for band values should be possible, but remains to be
#   implemented.  Unadorned parameter names imply constraints which
#   affect only the zeroth-order Chebyshev coefficient (i.e. the
#   constant value with wavelength).  They are therefore useful, and
#   behave as expected, if you are not allowing any wavelength
#   dependence in the parameter in question.  Any other use of
#   soft-coupled constraints (i.e. for parameters with non-constant
#   wavelength dependence) is inadvisable.

# Hard coupled-components constraints:
#   These can only be specified in terms of Chebyshev coefficients,
#   (see below).  It is not possible to implement hard-coupling in
#   terms of the actual band values.  Unadorned parameter names imply
#   constraints which affect only the zeroth-order Chebyshev
#   coefficient (i.e. the constant value with wavelength).  They are
#   therefore useful, and behave as expected, if you are not allowing
#   any wavelength dependence in the parameter in question.  If you
#   are allowing the parameters more freedom to vary with wavelength,
#   and you wish them to be fully-coupled then you must specify
#   constraints for all the free Chebyshev coefficients individually.
#   Hard coupling some, but not all, free Chebyshev coefficients for a
#   parameter is inadvisable.

# Individual band values:
#   If you wish to apply a constraint to a specific band, the usual
#   parameter names may be appended with "_bandlabel", where bandlabel
#   is the label of the band in question, as specified in parameter A1
#   of the GALFITM input file.  One may also append "_all" to
#   explicitly indicate all bands.
#   These contraints do not currently appear to be respected for
#   higher-order parameters (e.g. boxiness, fourier and bending modes).
#   If you need to constrain these parameters, please consider constraints
#   on the Chebyshev values (i.e. 'c_0' rather than just 'c')

# Cheybshev coefficient values:
#   If you wish to constrain specific Chebyshev coefficients, the
#   usual parameter names may be appended with "_i", where i
#   indicates the Chebyshev coefficient (i=0...nbands)