jasper countAll clarification

[Ram2399]

while using countAll for a particular filed as a Summary  calculation type does it count the null values or not?

Example:if i use countAll () for  the id which is having all null values it is showing result 0.if we use same on some not null values it is showinf result some number is this expected functionlaity of  jasper?i am thinking countAll() will consider both null and not null values ?

Thanks in Advance..