What information is on a passport bar code?

The FAQ page of the Online Passport website is https://pptform.state.gov/include/FAQ.htm --- excerpt --- Q:I don't have all the information I need to complete the form right now. Why can't I partially fill out the form and complete the rest by hand later? A:In addition to generating a completed application form, this website also creates a barcode that is placed at the top of the generated passport application form. This barcode contains the information gathered from the web page, and is later used to easily read in and process the information on your application. For the barcode to be generated correctly, all required fields must be completed at the time the form is submitted for creation. --- end excerpt --- The Feb 2008 version of the DS-11 passport application, which is created by the Wizard process, displays a regular barcode at the bottom right, as well as the 2-D code (referenced above) vertically at the top left. I had to print the application with 93% reduction to get it all on my HP Laser printer. Because of this code, you can't do the process twice then mix and match the two pages. I read the FAQ to mean that ALL the information you typed in is contained in it.