Via <para> a text paragraph inside <notes> is put into brackets. Starting with version 2.2.0 of UDDF it is always necessary to use <para> when inserting text — even if only one paragraph is needed.
<notes>
<notes>
(see also <notes>)
<notes>
<para>
This is a first paragraph.
</para>
<para>
This is the second paragraph.
</para>
<link ref="picture_1"/>
<para>
And this is the third paragraph. Before it via an <link/> element
a photo is inserted into the text.
</para>
</notes>