10 
ヘッダ

general-header
        = Cache-Control | Connection | Date
                        | Transfer-Encoding | Upgrade | Via | ・  ・  ・

request-header
        = Accept | Accept-Charset | Authorization
                        | Host | If-Modified-Since | If-Range
                        | Range | User-Agent | ・  ・  ・

response-header
        = Accept-Ranges | Age | ETag
                        | Location | Retry-After | ・  ・  ・

entity-header
        =  Content-Language | Content-Length | Content-MD5
                        | Content-Type | Expires | Last-Modified | ・  ・  ・