In section 4.7.6 step 3 under "If data is a Document", the following sentence:

"Let mime type be "application/xml" or "text/html" if Document is an HTML document, followed by ";charset=", followed by encoding."

is ambiguous since it can be read either as

A: Let mime type be ( "application/xml" or "text/html" ) if Document is an HTML document ...

or as

B: Let mime type be "application/xml" or ( "text/html" if Document is an HTML document ) ...

suggest rephrasing as follows:

"If Document is an HTML document, then let mime type be "text/html" followed by ";charset=" followed by encoding; otherwise, let mime type be "application/xml".

an even more simplified form would be:

"If Document is an HTML document, then let mime type be "text/html;charset=encoding"; otherwise, let mime type be "application/xml"."

in this case encoding should be set in italic to denote it is a variable corresponding to the same-named variable in the previous paragraph