I lost my library card but had seomeone else’s that belonged to the same library.
I scanned the barcode using Binary Eye (fdroid) (best scanner.) It was a 16-character CODABAR barcode mesasuring just under 2in/5cm wide and 1/4in/1cm long.
The First and last bytes were “A”, with 14 ASCII-encoded numbers between them. I replicated the bar code, printed it off, and got into my account.