A Note about Functions and NULL Qualifier Values 

Starting with SP6 Patch 0, the IS_NOT_NULL() function requires that ALL of a qualified field's qualifer values have NULL values in order to return a FALSE value. The prior behavior was that if ANY of a field's qualifier values had NULL values, it would return a FALSE value. This change means users now have the option of using IS_NULL() to test whether some of a qualified field's qualifier values are NULL, or using IS_NOT_NULL() to test whether all of a qualified field's qualifer values are NULLs.

This new behavior is summarized in the table below.

	No qualified links (or) Qualified links and ALL of them have a NULL qualifier value	Qualified links and NONE of them has a NULL qualifier value	Qualified links and SOME of them have NULL qualifier values
IS_NULL()*	TRUE	FALSE	TRUE
IS_NOT_NULL()**	FALSE	TRUE	TRUE

* can think of as “has any NULL values”

** can think of as “has any non-NULL values”

The behavior change also means that IS_NULL() and IS_NOT_NULL() are no longer inverse functions. To test the inverse of each function, use NOT(IS_NULL()) and NOT(IS_NOT_NULL()) respectively.