Why am I seeing an "Invalid XML character" error when importing a topic?

Some XML characters are invalid and cannot be imported into IXIASOFT CCMS.


I get an "Invalid XML character" error when trying to import a topic that has the following text:
When you open a note that has special Unicode characters (such as  or ) in the note accumulator, an error is displayed.  


There are certain characters that are not valid in XML.


Escape or remove the character from topic prior to importing it into the IXIASOFT CCMS.