Commercial vehicle certification 101

Since we have experience replacing bodies on some of our existing vehicles, we’re considering building our own vehicles with the garage services we have for our delivery operations rather than relying on a body company. As such, we’re trying to gain a better understanding of certification. Does this refer to the sticker that would go on our trucks when we’re finished building them? We’re also considering building vehicles for our other division’s operations in Canada, so would this be the same for those trucks?