Is there anymore documentation on the IDML HTMLItem specification and HTMLItem poster property?

I'm working with coding with the IDML documents and I'm looking for more information on the IDML HTMLItem. I have both the version 7 and version 8 of the IDML specification and have not found anymore information then a small mention in the "new elements" of version 8,

The HtmlItem element has been added as a child element to the element, element (see "Graphics" on page 91), element, element and element. This element is the embedded HTML item.

Has anyone has found anymore detailed information this specific object or it's properties? Specifically there is a property called, "Poster" that looks like thumbnail data. Here is my example:

            <HtmlItem Self="udc" HtmlContent="This &lt;i&gt;is an&lt;/i&gt; &lt;b&gt;HTML snippet &lt;/b&gt;&lt;b&gt;&lt;i&gt;DUDE&lt;/i&gt;&lt;/b&gt;." FixedDimensions="true" RelativeSubPath="This &lt;i&gt;is an&lt;/i&gt; &lt;b&gt;HTML snippet &lt;/b&gt;&lt;b&gt;&lt;i&gt;DUDE&lt;/i&gt;&lt;/b&gt;." ParentInterfaceChangeCount="" TargetInterfaceChangeCount="" LastUpdatedInterfaceChangeCount="" OverriddenPageItemProps="" HorizontalLayoutConstraints="FlexibleDimension FixedDimension FlexibleDimension" VerticalLayoutConstraints="FlexibleDimension FixedDimension FlexibleDimension" LocalDisplaySetting="Default" AppliedObjectStyle="n" Visible="true" Name="$ID/" ItemTransform="1 0 0 1 -50 -50">
                <Properties>
                    <Poster><![CDATA[iVBORw0KGgoAAAANSUhEUgAAAMgAAAAmCAYAAACBFtRsAAAFtklEQVR42u1cPY7yP...==]]></Poster>
                    <PathBoundingBox Left="0" Top="0" Right="200" Bottom="38" />
                    <GraphicBounds Left="0" Top="0" Right="200" Bottom="38" />
                </Properties>
                <TextWrapPreference Inverse="false" ApplyToMasterPageOnly="false" TextWrapSide="BothSides" TextWrapMode="None">
                    <Properties>
                        <TextWrapOffset Top="0" Left="0" Bottom="0" Right="0" />
                    </Properties>
                </TextWrapPreference>
            </HtmlItem>

I stripped out the full value of the Poster tag but I've pasted it into a bin at http://pastebin.com/s5ZfFfyW. Is this base64 encoded image data?

InDesign Documentation - http://www.adobe.com/devnet/indesign/documentation.html#idml

Solution

There is no additional documentation at this time. And in testing it looks like the poster property contains Base-64 encoded data.