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When the user enters a valid value in the control, the submit button will automatically get enabled. Until that point the submit button remains disabled. This automatically ensures that it is not possible to submit a form with an invalid value.
Note that controls that are optional do not cause the submit button to be disabled unless the value entered is invalid. As the figure above shows, there are no values in the optional Email Address and Phone fields but the form may be submitted. However, if the user enters an invalid value in one of the fields (required or not), the submit button will again be disabled by .
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