As I say, it confused me at first - I understand it now, but it is odd the way they have arranged it. I would have thought a simple calendar arrangement would have been more obvious. If they want to group it weekly, it is more logical to put a week number for each group (rather than the date), then the actual date against each entry.
As I alluded to, in programming you need to be extremely logical in how you group and order code, not just for your own benefit, but for others who need to modify the code later. I do actually assume the person who arranged this was not a programmer.