3.3.4 - Error prevention (legal, financial, data)

The intent of this success criterion is to help users with disabilities avoid serious consequences as the result of a mistake when performing an action that cannot be reversed. For example, purchasing non-refundable airline tickets or submitting an order to purchase stock in a brokerage account are financial transactions with serious consequences. Likewise, it may be an unrecoverable error if users unintentionally modify or delete data stored in a database that they later need to access.

For web pages that cause legal commitments or financial transactions for the user to occur, that modify or delete user-controllable data in data storage systems, or that submit user test responses, at least one of the following is true about the transaction:

• reversible
• checked
• confirmed