Name
correlation — 
      Indicates the linear correlation of this function or variable's
      randomness with a previously computed random variable
    
Content model
correlation :  varID,  corrCoef
     EMPTY
Attributes
varID - Identifies the variable or function output that helps
      determine the value of this random variable or function.
corrCoef - 
Description
      When present, this element indicates the parent function or
      variable is correlated with the referenced other function or
      variable in a linear sense, and gives the correlation
      coefficient for determining this function's random value based
      upon the correlating function(s) random value.