anchor.diff:  --------------------------------------------------
   *Input*:
   
  -<1> string expression
  -<2> integer expression
  -<3> integer expression
  +<1> string expression. If `null`, the function returns `null`.
  +<2> integer expression. If `null`, the function returns `null`.
  +<3> integer expression. If `null`, the function returns `null`.
   
   *Output*: string
   
  
positive.code: --------------------------------------------------
  *Input*:
  
  <1> string expression
  
  *Output*: string
  
  
negative.code: 
  *Output*: integer
  
  *Description*: Returns the starting position of the first occurrence of `pattern` within `source`. The optional `start` specifies the character position to start the search with. The first character position in `source` is indicated by the value 1. Not specifying `start` or specifying it as `null`, any negative value, 0 or 1, starts the search at the first character position. If `pattern` is not found within `source`, the value 0 is returned.
  
  [source, sql]
  --------------------------------------------------
  