The '&' character has special meaning within XML, just like it does in HTML. When you use a "CDATA" block for a script, it tells XML to treat everything as raw text. However, within an attribute value, the character always has special meaning. That's why the error says that the character '&' is a problem.
You need to use the special code for the '&' character, which is "&". The '&' is followed by the letters "amp" and then finished with a semi-colon. All five characters are required. This results in the following XML element:
Code:
<fieldval
field="usrCandid1"
value="component.Skill & fieldval:trtFinal >= 2"/>
You can find more details about this within the documentation. Go to the page below and see the section entitled Reserved XML Characters.
http://hlkitwiki.wolflair.com/index.php5/XML_Files