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Try validating this page: http://q.gotdns.com/w3.html (you can click the Validate! link in the document) validator output is: Validation Output: 1 Error 1. Error Line 28, Column 0: 18 up 164 days, 3:49, 1 user, load average: 0.00, 0.00, 0.00<br . Problems: a. markup is valid, there should not be an error b. the document only has 18 lines, the location given is incorrect. Often some random markup line is provided by the validator c. the cause is the   entry in column 17 on line 13, if these six characters are removed, no validation error is given complete document below: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Is this really invalid xhtml 1.1?</title> <link rel="stylesheet" type="text/css" media="screen" href="style/default-temp.css" /> </head> <body> <p><a href="http://validator.w3.org/check?uri=referer">Validate!</a></p> <p>an &ensp inserted in the paragraph below causes the w3c xhtml 1.1 validator service to incorrectly report an error in the column of the &ensp but at a random line in the document.</p> <p>root@hrudell:~# uptime; uname<br />  17:28:18 up 164 days, 3:49, 1 user, load average: 0.00, 0.00, 0.00<br /> Linux</p> </body> </html> Otherwise, I enjoy the validation services very much! Regards, Harald Rudell
*** This bug has been marked as a duplicate of bug 4892 ***