Because the shelves end up fitting a total of 18 cans, I needed a handy way of keeping track of what is in each row. Sure, you can know basically what is in each row by what the first can is, but that doesn't tell you how many are in each row. What I decided on was a white board strip placed on the stop for each row.
This way I'm able to tell, at a glance, what is on each row and what the date is on the items in that row. We've had some occasion to put similar items in the same row, and even with different dates. And that works just fine, so long as you can write a little smaller.