What is this? | O Gauge Railroading On Line Forum

<div id="{%=id%}" class="reveal-modal small h-alert-modal-popup" data-reveal>
    <div class="first-modal-focus focus-utility-element" tabindex="0" aria-label="Inside Modal"></div>

<h4 id="{%=id%}_title" class="margin-bottom-10 popup-title"></h4>
    <div id="{%=id%}_body" class="margin-bottom-10 popup-body">
        </div>

<ul id="{%=id%}ButtonGroup" class="button-group h-popup-buttons even-button-group even-1">
    <li id="{%=id%}Okay_buttonContainer"><a id="{%=id%}Okay" href="javascript:void(0);" class="button success no-margin-bottom h-alert-modal-ok-button" role="button">OK</a><script type="text/javascript">
        (function() {
            function {%=id%}Okay_click(event, data) {
            {%=id%}Popup.hide();
        }
        
                $('#{%=id%}Okay').on('click', {%=id%}Okay_click);
        })();
    </script></li></ul><a href="javascript:void(0);" class="close-reveal-modal" aria-label="Close Modal">&#215;</a><div class="last-modal-focus focus-utility-element" tabindex="0"></div>
</div>
<script type="text/javascript">
        (function() {
            {%=id%}Popup = new SS.Popup.ModalPopup('{%=id%}');
        })();
    </script>