A lot, apparently. Let's dive into 2D barcodes, high speed automation, printers, cryptographic signatures, postal mail and postage, and patents.
204 Barcode Standards
What happens when a bad bar code isn't covered up?: Modern U.S. Mail
Understanding FIM Marks on Envelopes
Usps Tracking
Intelligent Mail Barcode: What It Is and How to Read It
Package deal – USPS Employee News
204 Barcode Standards
204 Barcode Standards
DMM 505 Return Services