My grandpa’s grocery receipt printed with a thick blue stripe down the side. What does the blue stripe mean?

14. When (If Ever) You Should Ask the Store to Reprint the Receipt
Request a reprint if the blue stripe obscures essential details, such as transaction totals, item names, or store information. It’s especially critical if you need the receipt for returns, warranties, or reimbursement purposes. Most retailers are willing to accommodate such requests, provided they are made promptly after the transaction. Always review your receipt before leaving the store to catch any potential issues early.