This is what a uDoc document file might look like:
<doc>
<title>Document title</title>
<title>Last updated July 12, 2013</title>
<desc>This is a description of the document for mouseover use.</desc>
<!-- data can appear anywhere in the file for non-text data -->
<author>Author Name</author>
<!-- sect begins a section, nesting creates a subsection -->
<sect>
<!-- div is a grouping element, and is nestable with many types
a file can contain any number of divs, nested or not
-->
<div id="unique_in_file">
<!-- a sect title is optional, and is the content brought in by title xrefs -->
<title>Section title</title>
<!-- text elements like p can contain only UTF-8 text and inline elements -->
<p>Text contains only <ph class="em">inline</ph> elements.</p>
<ol> <!-- styletype decimal is the default -->
<li>First</li>
<li><p>Second</p>
<p>An added paragraph</p></li>
<li><p>Third</p>
<ul> <!-- styletype disc is the default -->
<li><p>Subitem a</p></li>
<li><p>Subitem b</p></li>
</ul>
<p>Para after list in same item</p>
</li>
<li>Fourth</li>
</ol>
</div>
<!-- xrefs provide indirection, bringing in content from elsewhere
a reference with an idref selects only the element with that id
an unqualified file or url xref selects all elements in the file
-->
<p>A paragraph after the list and div with a cross-reference, see
<xref src="file1.mxl" idref="div_id" class="titlexref">Text
for the xref (optional)</xref> for more info. This ends the para.</p>
<!-- index entries have multiple levels and sort strings in Frame format
the colons and brackets can be escaped with a \ if used in content
index entries can specify see or seealso attributes in which case
they reference another index entry, not the containing paragraph
-->
<p class="para_format">This contains a full para. White space
<idx id="aterm">Top level:secondary level[sort1:sort2]</idx>
<idx see="aterm">Synonym</idx>
in it is significant and is normalized to single spaces.</p>
</sect>
<sect>
<!-- the textref brings in the referenced content here, like a DITA conref -->
<textref src="file2.xml" idref="div_id"/>
<fig class="figure_format">
<title>Figure title</title>
<desc>This is an example of figure markup.</desc>
<!-- in a fig, content can be image or any kind of object
here the src is used only if the key is not defined
-->
<image key="onekey" src="myimage.png">
<alt>Text to use when image cannot be shown.</alt>
</image>
</fig>
<table class="table_format">
<title>Table Title</title>
<desc>This is an example of table markup.</desc>
<col width="20" />
<col width="50" />
<row type="head">
<cell>First col head</cell>
<cell>Second col head</cell>
</row>
<row type="body">
<cell>First col</cell>
<cell>Second col</cell>
</row>
<row type="foot">
<cell>First col foot</cell>
<cell>Second col foot</cell>
</row>
</table>
</sect>
<relref subjects="files" />
</doc>