Information in the HEADER which can not be changed/altered

What are the filed in the header whi开发者_StackOverflowch will be always present [99% atleast] and can not be altered ?

According to w3.org this header fields is not modifiable by javascript:

• Accept-Charset
• Accept-Encoding
• Connection
• Content-Length
• Cookie
• Cookie2
• Content-Transfer-Encoding
• Date
• Expect
• Host
• Keep-Alive
• Referer
• TE
• Trailer
• Transfer-Encoding
• Upgrade
• User-Agent
• Via
• Proxy-*
• Sec-*

The request. Everything else is optional. Host header is mandatory if using HTTP/1.1.