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+THE TRANSFORMATION SECTION
+    
+    The  transformation  section  is  used  to define the transformation
+    equations, to specify which parameters are to be altered  and  which
+    are  to  be  held constant during the fitting process, and to assign
+    initial values to the parameters.
+    
+    The transformation section begins with the  keyword  transformation,
+    followed  by  the  list  of  parameter declarations, followed by the
+    transformation equation.
+
+    Syntax
+        transformation
+        
+        fit  parameter = value, parameter = value, ...
+        
+        constant  parameter = value, parameter = value, ...
+        
+        label : expression  =  expression
+                (function)    (fit)
+    
+    The fit keyword begins a list of the  parameters  to  be  fit.   The
+    named   parameters   will   be   fit   if  they  are  present  in  a 
+    transformation equation.  The fit parameter values are used  as  the
+    initial guesses for the parameters.
+    
+    The  constant  keyword  begins  a  list of the parameters to be held
+    constant.  The named parameters will not be fit. Instead the  values
+    are  regarded  as  constant values in any transformation equation in
+    which they appear.  Constant parameter declarations are  used to fix
+    values  if  they are known, or to restrict the degrees of freedom of
+    the fit.
+    
+    All parameters, both fit and constant, must be declared  before  the
+    first  equations  in  which they appear.  There may be any number of
+    fit and constant parameter  declaration  statements.   Redefinitions
+    are  allowed,  i.e.,  it is possible to declare a parameter with the
+    fit keyword, and redefine it later with the constant  keyword.   The
+    inverse is also true.
+    
+    The  transformation  equations  are  composed of three elements: the
+    equation label, the function expression, and the fit expression.
+    
+    The label is used  to  assign  a  name  to  the  equation  and   fit
+    expression.   The  label can be any name not already in use. The ":"
+    after the label is necessary to delimit it  from  the  rest  of  the
+    transformation  equation  defintion.  Labels  are  used primarily to
+    associate the optional error, weight and  plot  equations  with  the
+    appropriate  transformation  equations.   However  these  labels can
+    also be used in expressions belonging to  subsequent  equations,  an
+    action  equivalent  to  replacing  them with the fit expression they
+    reference, before performing the actual evaluation.
+    
+    The function expression (left hand side of the "=" sign) is used  as
+    a  reference  expression,  i.e. an expression that has no fitting or
+    constant parameters in it. The  function  expression  contains  only
+    values  computed  from the input data which are known before the fit
+    starts.
+    
+    The fit  expression  (right  hand  side  of  the  "="  sign)  is  an
+    expression  which  contains the parameters, both those to be fit and
+    those that are fixed.  If this expression contains names defined  in
+    the  catalog  section  , it will be possible to perform the fit, but
+    will not be possible to apply the  transformations  in  the  forward
+    sense  to  program  observations  that  don't  have matching catalog
+    values.  If the number of transformations equations is greater  than
+    or  equal  to  the  total  number  of  catalog variables used in the
+    transformation equations, it MAY be possible to  invert  the  system
+    of  equations  and  so  evaluate  the  catalog variables for program
+    objects.
+    
+    
+    Example
+        
+        # Sample transformation section for the UBV system
+        
+        transform
+        
+        # V equation
+        
+        fit     v1 = 25.0, v2=1.03, v3=-0.17
+        VFIT :  V = v1 + v + v2 * (b - v) + v3 * x
+        
+        # B - V equation
+        
+        fit     b1 = 2.10, b2 = 1.15, b3=-0.12
+        const   b4 = 0.0
+        BVFIT : BV = b1 + b2 * (b - v) + b3 * x + b4 * (b - v) * x
+        
+        # U - B equation
+        
+        fit     u1 = 3.45, u2 = 1.063, u3=-0.30
+        const   u4=0.0
+        UBFIT : UB = u1 + u2 * (u - b) + u3 * x + u4 * (u - b) * x