accept                  Accept                   
accept_charset          Accept-Charset           
accept_encoding         Accept-Encoding          
accept_language         Accept-Language          
accept_ranges           Accept-Ranges            
age                     Age                      
allow                   Allow                    
authorization           Authorization            
cache_control           Cache-Control            
connection              Connection               
content_encoding        Content-Encoding         
content_language        Content-Language         
content_length          Content-Length           
content_location        Content-Location         
content_md5             Content-MD5              
content_range           Content-Range            
content_type            Content-Type             
date                    Date                     
etag                    ETag                     
expect                  Expect                   
expires                 Expires                  
from                    From                     
host                    Host                     
if_match                If-Match                 
if_modified_since       If-Modified-Since        
if_none_match           If-None-Match            
if_range                If-Range                 
if_unmodified_since     If-Unmodified-Since      
last_modified           Last-Modified            
location                Location                 
max_forwards            Max-Forwards             
mime_version            MIME-Version
pragma                  Pragma                   
pr_authenticate         Proxy-Authenticate       
pr_authorization        Proxy-Authorization      
range                   Range                    
referer                 Referer                  
retry_after             Retry-After              
server                  Server                   
te                      TE                       
trailer                 Trailer                  
transfer_encoding       Transfer-Encoding        
upgrade                 Upgrade                  
user_agent              User-Agent               
vary                    Vary                     
via                     Via                      
warning                 Warning                  
www_authenticate        WWW-Authenticate