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Error Prevention

Must

Section 508:

  • §1194.31(a)
  • §1194.31(b)

WCAG 2.0:

  • 3.3.4

Errors must be prevented for legal commitments and financial data

When data being entered is part of a legal commitment or is financial data, error prevention must be used to ensure that users with disabilities do not face serious consequences due to a mistake. Some legal and financial actions can not be reversed and thus making a mistake can be serious. This includes user settable data such as data that is stored or that is submitted as part of a challenge.

iOS Example

A form allows the user to enter bank account information to set up direct
deposit.  Once the user activates the submit button, the form provides some
client side based checking of the savings/check account number and bank
routing number as well as the other fields to determine if any errors can
be caught prior to online submission

iOS Failure

A form allows the user to enter bank account information to set up direct
deposit.  Once the user activates the submit button, the form is submitted
electronically with no client side error checking.

Android Example

A form allows the user to enter bank account information to set up direct
deposit.  Once the user activates the submit button, the form provides some
client side based checking of the savings/check account number and bank
routing number as well as the other fields to determine if any errors can
be caught prior to online submission.

Android Failure

A form allows the user to enter bank account information to set up direct
deposit.  Once the user activates the submit button, the form is submitted
electronically with no client side error checking.

HTML Example

A site used to pay a cable bill asks for the user's checking account
number, the bank's routing number, and the dollar amount to pay.  When the
user activates the "pay" button a screen appears asking the user
to confirm his/her choices and then the user must activate the
"complete transaction" button to complete paying the bill.

HTML Failure

A site used to pay a cable bill asks for the user's checking account
number, the bank's routing number, and the dollar amount to pay.  When the
user activates the "pay" button the transaction is completed and
there is no confirmation screen and the data is not checked.  The payment
is not reversible once completed.

Remediating

Developers must provide at least one of the following methods to prevent errors:

  1. Allow the submission to be reversible
  2. Allow the user to confirm the submission details entered
  3. Check the submission details for errors before completing the submission
  4. Prevent entering of invalid data such as entering alpha characters in a numeric field.

Testing

Recommended tool/method: Manual

Provide error prevention for legal commitments and financial data (Implied Global)
  1. Open the module
  2. Determine if legal commitments or financial data will occur
  3. Verify that at least one of the following error prevention methods is used:
    • The submission is reversible
    • The submission is checked for errors
    • The submission is confirmed by the user
    • Invalid data is ignored or stripped at time of entry
More in this category: Error Alerts »