Search in a specific field of a comment:

<SEARCH>
  <MEDIA>
    <COMMENTS>
      <COMMENT>
        <TITLE operator="contains">Music</TITLE>
      </COMMENT>
    </COMMENTS>
  </MEDIA>
</SEARCH>

Search in all the fields:

<SEARCH>
  <MEDIA>
    <COMMENT>
      <FULLTEXT>Music</FULLTEXT>
    </COMMENT>
  </MEDIA>
</SEARCH>

NB: the node COMMENTS around the COMMENT isn't mandatory

Search for a specific type of comment:

<SEARCH>
  <MEDIA>
    <COMMENT>
      <TYPE operator="=">UserMessage</TYPE>
      <TYPE operator="=">ModeratorMessage</TYPE>
    </COMMENT>
  </MEDIA>
</SEARCH>

This query will find the elements with comments of type UserMessage or ModeratorMessage.

Search for a comment created today on a Nectil element:

<SEARCH>
  <MEDIA>
    <COMMENT>
      <CREATIONDATE>today</CREATIONDATE>
    </COMMENT>
  </MEDIA>
</SEARCH>

Search for an element where a comment is present

<SEARCH>
  <MEDIA>
    <COMMENT operator="exists"/>
  </MEDIA>
</SEARCH>

Search for an element where no comment is present

<SEARCH>
  <MEDIA>
    <COMMENT operator="not_exists">
      <CREATIONDATE>today</CREATIONDATE>
    </COMMENT>
  </MEDIA>
</SEARCH>

Finds the elements that were not commented today.