Firstly the person needs to define exactly what it is needed for. So they need to make a decision as to what information they want it to contain and what will be provided at the end. So you need to make a decision regarding the following:-

1. Is your system going to provide you with information relating to employee time and attendance the amount of time a person has had off for either vacation, sick or personal reasons on a person by person basis. Or is the system you are devising going to provide you with just the total number of days that each person has taken off?