do report parameters have to be declared in the default package?

After I entered default package name in the existing data model my attempts to generate sample xml would fail with the following error:

XML Parsing Error: mismatched tag. Expected: </img>.
Location: http://sfdras102.polk.com:9704/xmlpserver/servlet/xdo
Line Number 2, Column 580:

After I declared parameter in the package spec the error has gone away. Do all report parameters have to be declared in the default package? Even if parameter value isn't used or changed by the package?