bal
<<<
i 2007/03/01 23:00:00 A
o 2007/03/02 01:00:00
i 2007/03/11 23:00:00 B
o 2007/03/12 01:00:00
>>>1
                2.0h  A
                2.0h  B
--------------------
                4.0h
>>>2
=== 0