
This field is set to the date of the month when interest should be charged.
The allowable range is 1 through 31 where 31 signifies Last Working Day of the month. If the day set is more than the number of days in a particular month, then the charge will be applied on the last day.
A special value of 55 will cause interest to be charged differently for each account, and will use the anniversary of the date the account opened.