In the section "Specifying a Document's Character Encoding", it is stated that polyglot markup uses UTF-8. It then says that the prefered way to indicate this encoding is with a Byte Order Mark.
This is not advisable I feel due to: UTF-8 not requiring a BOM ; that it could cause problems with applications (apparently MSIE does or did have a problem) and programing languages (apparently inc. Java ); it causes otherwise valid ASCII to stop being ASCII.
As such, I would swap the prefered method for indicating UTF inside the document and add a note about using the BOM.
* By using <meta charset="UTF-8"/> (the HTML encoding declaration)(preferred).
* By using the Byte Order Mark (BOM) character (could cause problems in some situations).
We are waiting for the editor to take action on bug 13392
*** This bug has been marked as a duplicate of bug 13392 ***