Name
uncertainty — 
      Describes statistical uncertainty bounds and any correlations for
      a parameter or function table.
    
Attributes
effect - Indicates how uncertainty bounds are interpreted (enumerated)
  
additive
multiplicative
percentage
absolute
Description
      This optional element is used in function and parameter
      definitions to describe statistical variance in the possible
      value of that function or parameter value. Only Gaussian
      (normal) or uniform distributions of continuous random variable
      distribution functions are supported.