[oXygen-user] How to get the location of "invalid UTF-8 characters"?

Hi Folks, I have a large XHTML file. Apparently, somewhere in the file is an invalid Unicode character because when I drag-and-drop the file into Oxygen I get the error message: Cannot open the specified file: Got a character encoding exception. File encoding (UTF-8) does not support all characters from the current file. The problem is this: Where is the invalid UTF-8 character? Is there a way to get Oxygen to tell me where -- what character position -- it detected the invalid Unicode character? /Roger