<li data-link-for="PaymentValidationErrors">By matching the

members of <var>errorFields</var> to input fields in the user

agent's UI, indicate to the end-user that something is wrong with

the data of the payment response. For example, a user agent might

draw the user's attention to the erroneous <var>errorFields</var>

in the browser's UI and display the value of each field in a

manner that helps the user fix each error. Similarly, if the <a>

error</a> member is passed, present the error in the user

agent's UI. In the case where the value of a member is the

empty string, the user agent MAY substitute a value with a

suitable error message.

</li>

<li>Otherwise, if <var>errorFields</var> was not passed, signal to

the end user to attempt to retry the payment. Re-enable

any UI element that affords the end-user the ability to retry

accepting the payment request.