6.2.3 List of Character Sets Supported in the Response
The Accept-Charset header field of the GET method request shall specify the character set of the object to be retrieved. If the Accept-Charset header field of the GET method is not present, or the origin server does not support the specified character set, the character set of the response will be at the discretion of the origin server.
Note
Typically the user of a user agent does not have control over the Accept-Charset header field. An optional parameter specifies the character set to be used in the returned object.