What does the bar code on the top right (near the stamp) of an envelope signify?

Question

Some of us know that on some envelopes, there is a bar code located at the bottom right of the envelope, which signify the delivery address for a computer to read when mail is sent to help speed up the process. On some of these envelopes, there is also a smaller set of about 5 lines that look like barcodes also, which are located at the top right near where the stamp goes. What do these lines signify?

Answer 1

That code simply lets the machine know which side is up. In other words, how to position the envelope (front, back, top and bottom) so that the scanner can read the address bar code or zip code.

Answer 2

This "bar code" tells the machine that the envelope already has a bar code on it, so the machine does not have to search for the ZIP code and print the bar code. Often the machine fails to "notice" this indicator and re-barcodes it anyway, but if the machine senses it properly, then it saves that step.