help regarding this query

[icemonster]

SELECT [EMP ID], [DATE], [TIME], 
(Select count(*) from [tblPunchCard] where [EMP ID] = a.[EMP ID] and [Date]+[Time] <= a.[Date]+a.[Time]) AS Num, 
iif(Num mod 2 =1, "In" ,"Out") AS InOut, 
iif(InOut="In", Num, Num-1) AS Pair
FROM [tblPunchCard] AS a;

i found this code on this site and i am trying to understand it, basically what i am trying to do is that don't assign an out or don't pair the records if their dates are not equal.

any help is appreciated.