SAXParseException The processing instruction target matching "[xX][mM][lL]"

This is from an officemate:

SAXParseExceptionThe processing instruction target matching "[xX][mM][lL]"

Diagnosis:

"the processing instruction target matching "[xX][mM][lL]" is not allowed"
is a common problem that means there are some white spaces before the XML
declaration.

some link