Test using setAttributeNode() multiple times with "compatible" names and "incompatible" names." On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". Testing: FooBar PASS document.documentElement.attributes.length is 1 PASS document.documentElement.attributes.length is 0 PASS document.documentElement.attributes.length is 1 PASS document.documentElement.attributes.length is 0 Testing: foobar PASS document.documentElement.attributes.length is 1 PASS document.documentElement.attributes.length is 0 PASS document.documentElement.attributes.length is 1 PASS document.documentElement.attributes.length is 0 Testing: FOOBAR PASS document.documentElement.attributes.length is 1 PASS document.documentElement.attributes.length is 0 PASS document.documentElement.attributes.length is 1 PASS document.documentElement.attributes.length is 0 PASS successfullyParsed is true TEST COMPLETE