(als: I'm not sure modifying data should be included here. You can always modify it again if you make a mistake.)
(als: Do we really need this? This success criteria is about the user making mistakes, not "errors". We have defined errors as something the user does that is not allowed by the delivery unit. Here we have things that are allowed by the delivery unit but are not what the user intended.)
Transactions that ....
The intent of this success criterion is to help users with disabilities avoid serious consequences as the result of a mistake. For example, purchasing non-refundable airline tickets or submitting an order to purchase stock in a brokerage account are financial transactions with serious consequences. If a user has made a mistake on the date of air travel, he or she could end up with a ticket for the wrong day which can't be exchanged. If the user made a mistake on the number of stock shares to be purchased he or she could end up purchasing more stock than intended. Both of these types of mistakes can be very costly.
Users with disabilities may be more likely to make mistakes. People with learning disabilities may transpose numbers and letters and those with motor disabilities may hit keys by mistake. Providing the ability to reverse actions allows users to correct a mistake that resulted in serious consequences. Providing the ability to review and correct information gives the user an opportunity to detect a mistake before taking an action that has serious consequences.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 2.5 L2 SC1.
Instructions: Select the situation(s) below that match your content. Beneath it, are the option(s) that are known and documented to be sufficient for that situation. For the technology-specific techniques, see the options for the technology you are using listed immediately below.
Situation A: An application which causes a legal transaction, such as submitting an income tax return, to occur:
Situation B: A form which, upon submission, causes a purchase of goods or services to occur:
Situation C: An action which causes information to be deleted:
Situation D: A testing application:
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
Providing safeguards to avoid serious consequences resulting from mistakes helps users with all disabilities who may be more likely to make mistakes.
A Web retailer offers online shopping for customers. When an order is submitted, the order information, including items ordered, quantity of each ordered, shipping address, and payment method, are displayed allowing the user to inspect the order for correctness. The user can either confirm the order or make changes.