anchor.diff:  FROM DUAL;
   ```
   
  -* This function returns the value 1 because a one-second boundary is
  +* This function returns the value of 1 because a one-second boundary is
   crossed even though the two timestamps differ by only one microsecond.
   +
   ```
  
positive.code: [[date_difference_in_quarter]]
  ==== Date Difference in QUARTER
  
  * This function returns the value of 3 because a three-quarter boundary is crossed.
  +
  ```
  SELECT DATEDIFF( QUARTER
  
negative.code: [[the_first_week_of_year]]
  ==== The first week of year
  
  The first week of the year is the week in which January 1 occurs. Changing the first week of the year is not supported.  
  
  [[negative_or_zero]]
  ==== Negative or zero
  