A value of "true" indicates that all cells have the potential for content values. If set to "false" Attribute and CoordinateRegion should be used to define the sparse areas of the NCube, those that have no content by definition. For example a cross-tabulation between Household Type (Family, Non-Family) and Number of persons in Household (1,2,3,4,5,6,7+) would need an attribute for Family/1 Person as this will always be empty due to the definition of Family as two or more related persons.