File identification 
Uniquely identifies the file per month, consisting of 4 digits, for example: 0703

The first two digits are from the days of the month from the file creation date.
So if the file creation date is June 7, 2010 then the first two digits are 07.

The last two digits is a sequence number starting with 1. With each delivery on the same day that number increments with 1.
So if on June 7, 2010 the ClieOp file is delivered for the 3rd time, the last two digits are 03.
