AUI Form Validation For file uploads with extension

<aui:input type="file" name="field2" >

    <!--
    For use with input type="file"
    Only allow file uploads with this extension.
    Specify multiple values either comma delimted 'jpg, png',
    whitespace delimited 'jpg png', or pipe 'jpg|png' delimited.
    Do not include the period before the extension
    -->
    <aui:validator name="acceptFiles">
        'jpg, png'
    </aui:validator>
   
</aui:input>

AUI Form Validator Taglib

< aui:input name="field1" >
    <!-- Example with multiple validators -->

    <!-- Make the field required. If the field is empty, form will not submit -->
    <aui:validator name="required" />

    <!-- Only allow digits in the field -->
    <aui:validator name="digits" />

    <!-- Make sure field value is between 1 and 100 characters in length -->
    <aui:validator name="range" >
    [1,100]
    </aui:validator >

</aui:input >