ACCEPT (24)

Acceptable media types.

ACCEPT-CHARSET (25)

Acceptable character sets.

ACCEPT-ENCODING (26)

Acceptable content-coding values.

ACCEPT-LANGUAGE (27)

Acceptable natural languages.

ACCEPT-RANGES (42)

Types of range requests that are accepted.

AGE (48)

An estimate of the amount of time since the response was generated at the origin server.

ALLOW (7)

Methods supported by the server.

AUTHORIZATION (28)

Authorization credentials used for a request.

CACHE-CONTROL (49)

Cache control directives.

CONNECTION (23)

Options that are specified for a particular connection and must not be communicated by proxies over further connections.

CONTENT-BASE (50)

Base Uniform Resource Identifier (URI) for resolving relative URLs within the entity.

CONTENT-ENCODING (29)

Any additional content codings that have been applied to the entire resource.

CONTENT-ID (3)

Content identification.

CONTENT-LANGUAGE (6)

Language in which the content is presented.

CONTENT-LENGTH (5)

Size of the resource, in bytes.

CONTENT-LOCATION (51)

Resource location for the entity enclosed in the message.

CONTENT-MD5 (52)

MD5 digest of the entity-body for the purpose of providing an end-to-end message integrity check (MIC) for the entity-body. For more information, see RFC1864, The Content-MD5 Header Field, at ftp://ftp.isi.edu/in-notes/rfc1864.txt.

CONTENT-RANGE (53)

Location in the full entity-body where the partial entity-body should be inserted and the total size of the full entity-body.

CONTENT-TRANSFER_ENCODING (2)

Additional content coding that has been applied to the resource.

CONTENT-TYPE (1)

Content type of the resource, such as text/html.

COOKIE (44)

Cookies associated with the request.

DATE (9)

Date and time at which the message was originated.

ETAG (54)

Entity tag for the associated entity.

EXPECT (68)

Expect header, which indicates whether the client application should expect 100 series responses.

EXPIRES (10)

Date and time after which the resource should be considered outdated.

FROM (31)

E-mail address for the human user who controls the requesting user agent if the From header is given.

HOST (55)

Internet host and port number of the resource being requested.

IF-MATCH (56)

Contents of the If-Match request-header field.

IF-MODIFIED-SINCE (32)

Contents of the If-Modified-Since header.

IF-NONE-MATCH (57)

Contents of the If-None-Match request-header field.

IF-RANGE (58)

Contents of the If-Range request-header field. This header allows the client application to check if the entity related to a partial copy of the entity in the client application's cache has not been updated. If the entity has not been updated, send the parts that the client application is missing. If the entity has been updated, send the entire updated entity.

IF-UNMODIFIED-SINCE (59)

Contents of the If-Unmodified-Since request-header field.

LAST-MODIFIED (11)

Date and time at which the server believes the resource was last modified.

LOCATION (33)

Absolute URI.

MAX (75)

Not a query flag. This indicates the maximum value of an * value.

MAX-FORWARDS (60)

Number of proxies or gateways that can forward the request to the next inbound server.

MIME-VERSION (0)

Version of the MIME protocol that was used to construct the message.

MSTHEMECOMPATIBLE

Enables Windows XP user themes in the browser window.

PRAGMA (17)

Implementation-specific directives that might apply to any recipient along the request/response chain.

PROXY-AUTHENTICATE (41)

Authentication scheme and realm returned by the proxy.

PROXY-AUTHORIZATION (61)

Header that is used to identify the user to a proxy that requires authentication. This header can only be retrieved before the request is sent to the server.

PROXY-CONNECTION (69)

Proxy-Connection header.

PUBLIC (8)

Methods available at this server.

RANGE (62)

Byte range of an entity.

RAW-HEADERS (21)

All the headers returned by the server. Each header is terminated by \0. An additional \0 terminates the list of headers.

RAW-HEADERS-CRLF (22)

All the headers returned by the server. Each header is separated by a carriage return/line feed (CR/LF) sequence.

REFERER (35)

URI of the resource where the requested URI was obtained.

REQUEST-METHOD (45)

Verb that is used in the request, typically GET or POST.

RETRY-AFTER (36)

Amount of time the service is expected to be unavailable.

SERVER (37)

Information about the software used by the origin server to handle the request.

SET-COOKIE (43)

Value of the cookie set for the request.

STATUS-CODE (19)

Status code returned by the server. For a list of possible values, see HTTP Status Codes.

STATUS-TEXT (20)

Any additional text returned by the server on the response line.

TITLE (38)

Obsolete. Maintained for legacy application compatibility only.

TRANSFER-ENCODING (63)

Type of transformation that has been applied to the message body so it can be safely transferred between the sender and recipient.

UNLESS-MODIFIED-SINCE (70)

Unless-Modified-Since header.

UPGRADE (64)

Additional communication protocols that are supported by the server.

URI (13)

Some or all of the URIs by which the Request-URI resource can be identified.

USER-AGENT (39)

Information about the user agent that made the request.

VARY (65)

Header that indicates that the entity was selected from a number of available representations of the response using server-driven negotiation.

VERSION (18)

Last response code returned by the server.

VIA (66)

Intermediate protocols and recipients between the user agent and the server on requests and between the origin server and the client on responses.

WARNING (67)

Additional information about the status of a response that might not be reflected by the response status code.

WWW-AUTHENTICATE (40)

Authentication scheme and realm returned by the server.