Name
independentVarRef — References a predefined signal as an input to a function
Content model
independentVarRef :  varID,  [min],  [max],  [extrapolate]
     EMPTY
Attributes
| varID - the internal XML identifier for the input signal | 
| min (optional) - the allowable lower limit for the input signal | 
| max (optional) - the allowable upper limit for the input signal | 
| extrapolate (optional) - extrapolation flags for IV out-of-bounds | 
Description
An independentVarRef more fully describes the input mapping    
 of the function by pointing to a separate breakpoint definition 
 element. This allows common breakpoint values for many tables.