In the following example, the type redClass is missing, and therefore cannot be resolved. You must either remove or edit the reference, or add the type to your code.
$set ILDOC"cbloutput.xml" class-id new. *>> <summary> *>> Contains the name of <see cref="redClass" /><see cref="whiteClass" /><see cref="blue" />. *>> </summary> 01 blue string. ... end class. class-id whiteClass. ... end class.