Yellow boxes on tickets

What are those yellow boxes on the tickets supposed to symbolize? Is it just an easier way for them to identify which employee on the train punched the ticket? My first guess was it showed what car you are seated in. But that doesn't makes sense because most trains operate more than 7 cars.

I beleive they reprosent the days of the week that ticket was used on.

The yellow boxes on monthly and weekly tickets are there for "punch days'. On various times during the month, we are given instructions to punch a certain block on each ticket. This is done in an attempt to help prevent ticket fraud. it gives us a chance 4 or 5 times a month to examine the tickets.

Makes sense. These were on one way tickets though. I guess the reason they are on the one way tickets too is because they are printed on the same stock as the monthly tickets?

One way tickets are a different story, If you are going west on any train with a one way, we punch blocks 6 when you get on, 5 for any junction, and 4 and lift the ticket after jamaica. if you are heading east, we punch 1 when you get on, and 2 at any junction, and 3 and lift after jamaica. The round trips are punched accordingly, three boxes one way, the other 3 in the opposite direction.