Patch Code is a barcode developed by Kodak for use in automated scanning.
The bars are separated by three narrow spaces, so the Patch Code symbols are a fixed length.
In that situation, the scanner may just take the required action and not transfer the Patch Code image to the computer.
Before scanning, the document is prepared by inserting pages that only have a Patch 4 on them before and after the color sections.
Kodak's Capture Software assigns these default actions:[3] TWAIN has a facility for Patch Codes.