When "Source" attribute is "INLINE": use content of HTTP_RESPONSE_ENCODING and force http response encoding to this value.
When "Source" attribute is "REQUEST": use Accept-Charset http request header sent by User-Agent to determine http response encoding. Use UTF-8 if Accept-Charset is missing.
<HTTP_RESPONSE_ENCODING Source="INLINE">ISO-8859-1</HTTP_RESPONSE_ENCODING>
or
<HTTP_RESPONSE_ENCODING Source="REQUEST"/>