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# 3.3.4 Error Prevention (Legal, Financial, Data)

- Level: AA
- Guideline: 3.3 Input Assistance
- Principle: 3 Understandable

## What it is

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:

- **Reversible:** Submissions are reversible.
- **Checked:** Data entered by the user is checked for input errors and the user is provided an opportunity to correct them.
- **Confirmed:** A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.

## How to test

- Check: Submissions are reversible.
- Check: Data entered by the user is checked for input errors and the user is provided an opportunity to correct them.
- Check: A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.
- Use the sufficient techniques below as acceptable methods when applicable.

## Sufficient techniques (W3C)

- G164: Providing a stated time within which an online request (or transaction) may be amended or canceled by the user after making the request
- G98: Providing the ability for the user to review and correct answers before submitting
- G155: Providing a checkbox in addition to a submit button
- G99: Providing the ability to recover deleted information
- G168: Requesting confirmation to continue with selected action

## Advisory techniques (W3C)

- SCR18: Providing client-side validation and alert
- G199: Providing success feedback when data is submitted successfully

## Resources

- WCAG 2.2 SC: https://www.w3.org/TR/WCAG22/#error-prevention-legal-financial-data
- Understanding: https://www.w3.org/WAI/WCAG22/Understanding/error-prevention-legal-financial-data.html
- Quick reference: https://www.w3.org/WAI/WCAG22/quickref/?versions=2.2#error-prevention-legal-financial-data

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