Comment 1 for bug 170466

As a temporary solution, the XML editor already works,
either with inkscape:userattributes="foo=bar;baz=qux"
attributes, or with rta:foo="bar" rta:baz="qux" attributes
(though the latter would require that the outermost <svg>
element include an attribute
xmlns:rta="http://rta.nsw.gov.au/something.dtd"; that URL
doesn't need to exist, it's just a string identifier).