Registries included below
Expert Review
Graham Klyne
[RFC5504] specified that no new header fields be registered that begin with "Downgraded-". That restriction is now lifted, per [RFC6857].
See section 8.3.1 of [RFC7231] for information on registering new HTTP Header Fields.
Header Field Name | Template | Protocol | Status | Reference |
A-IM | http | [RFC4229] | ||
Accept | http | standard | [RFC7231, Section 5.3.2] | |
Accept-Additions | http | [RFC4229] | ||
Accept-Charset | http | standard | [RFC7231, Section 5.3.3] | |
Accept-Datetime | http | informational | [RFC7089] | |
Accept-Encoding | http | standard | [RFC7231, Section 5.3.4][RFC7694, Section 3] | |
Accept-Features | http | [RFC4229] | ||
Accept-Language | http | standard | [RFC7231, Section 5.3.5] | |
Accept-Language | [RFC4021] | |||
Accept-Patch | http | [RFC5789] | ||
Accept-Ranges | http | standard | [RFC7233, Section 2.3] | |
Age | http | standard | [RFC7234, Section 5.1] | |
Allow | http | standard | [RFC7231, Section 7.4.1] | |
ALPN | http | standard | [RFC7639, Section 2] | |
Also-Control | netnews | obsoleted | [RFC1849][RFC5536] | |
Alt-Svc | http | standard | [RFC7838] | |
Alt-Used | http | standard | [RFC7838] | |
Alternate-Recipient | [RFC4021] | |||
Alternates | http | [RFC4229] | ||
Apply-To-Redirect-Ref | http | [RFC4437] | ||
Approved | netnews | standard | [RFC5536] | |
Archive | netnews | standard | [RFC5536] | |
Archived-At | standard | [RFC5064] | ||
Archived-At | netnews | standard | [RFC5064] | |
Article-Names | netnews | obsoleted | [RFC1849][RFC5536] | |
Article-Updates | netnews | obsoleted | [RFC1849][RFC5536] | |
Authentication-Control | http | experimental | [RFC-ietf-httpauth-extension-09, Section 4] | |
Authentication-Info | http | standard | [RFC7615, Section 3] | |
Authentication-Results | standard | [RFC7601] | ||
Authorization | http | standard | [RFC7235, Section 4.2] | |
Auto-Submitted | standard | [RFC3834 section 5] | ||
Autoforwarded | [RFC4021] | |||
Autosubmitted | [RFC4021] | |||
Base | MIME | obsoleted | [RFC1808][RFC2068 Section 14.11] | |
Bcc | standard | [RFC5322] | ||
Body | none | reserved | [RFC6068] | |
C-Ext | http | [RFC4229] | ||
C-Man | http | [RFC4229] | ||
C-Opt | http | [RFC4229] | ||
C-PEP | http | [RFC4229] | ||
C-PEP-Info | http | [RFC4229] | ||
Cache-Control | http | standard | [RFC7234, Section 5.2] | |
CalDAV-Timezones | http | standard | [RFC7809, Section 7.1] | |
Cc | standard | [RFC5322] | ||
Close | http | reserved | [RFC7230, Section 8.1] | |
Comments | standard | [RFC5322] | ||
Comments | netnews | standard | [RFC5536][RFC5322] | |
Connection | http | standard | [RFC7230, Section 6.1] | |
Content-Alternative | MIME | [RFC4021] | ||
Content-Base | http | obsoleted | [RFC2068][RFC2616] | |
Content-Base | MIME | obsoleted | [RFC2110][RFC2557] | |
Content-Description | MIME | [RFC4021] | ||
Content-Disposition | http | standard | [RFC6266] | |
Content-Disposition | MIME | [RFC4021] | ||
Content-Duration | MIME | [RFC4021] | ||
Content-Encoding | http | standard | [RFC7231, Section 3.1.2.2] | |
Content-features | MIME | [RFC4021] | ||
Content-ID | http | [RFC4229] | ||
Content-ID | MIME | [RFC4021] | ||
Content-Identifier | [RFC4021] | |||
Content-Language | http | standard | [RFC7231, Section 3.1.3.2] | |
Content-Language | MIME | [RFC4021] | ||
Content-Length | http | standard | [RFC7230, Section 3.3.2] | |
Content-Location | http | standard | [RFC7231, Section 3.1.4.2] | |
Content-Location | MIME | [RFC4021] | ||
Content-MD5 | http | [RFC4229] | ||
Content-MD5 | MIME | [RFC4021] | ||
Content-Range | http | standard | [RFC7233, Section 4.2] | |
Content-Return | [RFC4021] | |||
Content-Script-Type | http | [RFC4229] | ||
Content-Style-Type | http | [RFC4229] | ||
Content-Transfer-Encoding | MIME | [RFC4021] | ||
Content-Type | http | standard | [RFC7231, Section 3.1.1.5] | |
Content-Type | MIME | [RFC4021] | ||
Content-Version | http | [RFC4229] | ||
Control | netnews | standard | [RFC5536] | |
Conversion | [RFC4021] | |||
Conversion-With-Loss | [RFC4021] | |||
Cookie | http | standard | [RFC6265] | |
Cookie2 | http | obsoleted | [RFC2965][RFC6265] | |
DASL | http | standard | [RFC5323] | |
DAV | http | standard | [RFC4918] | |
DL-Expansion-History | [RFC4021] | |||
Date | http | standard | [RFC7231, Section 7.1.1.2] | |
Date | standard | [RFC5322] | ||
Date | netnews | standard | [RFC5536][RFC5322] | |
Date-Received | netnews | obsoleted | [RFC0850][RFC5536] | |
Default-Style | http | [RFC4229] | ||
Deferred-Delivery | [RFC4021] | |||
Delivery-Date | [RFC4021] | |||
Delta-Base | http | [RFC4229] | ||
Depth | http | standard | [RFC4918] | |
Derived-From | http | [RFC4229] | ||
Destination | http | standard | [RFC4918] | |
Differential-ID | http | [RFC4229] | ||
Digest | http | [RFC4229] | ||
Discarded-X400-IPMS-Extensions | [RFC4021] | |||
Discarded-X400-MTS-Extensions | [RFC4021] | |||
Disclose-Recipients | [RFC4021] | |||
Disposition-Notification-Options | [RFC4021] | |||
Disposition-Notification-To | [RFC4021] | |||
Distribution | netnews | standard | [RFC5536] | |
DKIM-Signature | standard | [RFC6376] | ||
Downgraded-Bcc | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Cc | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Disposition-Notification-To | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Final-Recipient | standard | [RFC6857 Section 3.1.10] | ||
Downgraded-From | obsoleted | [RFC5504][RFC6857 Section 3.1.10] | ||
Downgraded-In-Reply-To | standard | [RFC6857 Section 3.1.10] | ||
Downgraded-Mail-From | obsoleted | [RFC5504][RFC6857 Section 3.1.10] | ||
Downgraded-Message-Id | standard | [RFC6857 Section 3.1.10] | ||
Downgraded-Original-Recipient | standard | [RFC6857 Section 3.1.10] | ||
Downgraded-Rcpt-To | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-References | standard | [RFC6857 Section 3.1.10] | ||
Downgraded-Reply-To | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Resent-Bcc | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Resent-Cc | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Resent-From | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Resent-Reply-To | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Resent-Sender | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Resent-To | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Return-Path | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-Sender | obsoleted | [RFC5504][RFC6857] | ||
Downgraded-To | obsoleted | [RFC5504][RFC6857] | ||
Encoding | [RFC4021] | |||
Encrypted | [RFC4021] | |||
ETag | http | standard | [RFC7232, Section 2.3] | |
Expect | http | standard | [RFC7231, Section 5.1.1] | |
Expires | http | standard | [RFC7234, Section 5.3] | |
Expires | [RFC4021] | |||
Expires | netnews | standard | [RFC5536] | |
Expiry-Date | [RFC4021] | |||
Ext | http | [RFC4229] | ||
Followup-To | netnews | standard | [RFC5536] | |
Forwarded | http | standard | [RFC7239] | |
From | http | standard | [RFC7231, Section 5.5.1] | |
From | standard | [RFC5322][RFC6854] | ||
From | netnews | standard | [RFC5536][RFC5322] | |
Generate-Delivery-Report | [RFC4021] | |||
GetProfile | http | [RFC4229] | ||
Hobareg | http | experimental | [RFC7486, Section 6.1.1] | |
Host | http | standard | [RFC7230, Section 5.4] | |
HTTP2-Settings | http | standard | [RFC7540, Section 3.2.1] | |
IM | http | [RFC4229] | ||
If | http | standard | [RFC4918] | |
If-Match | http | standard | [RFC7232, Section 3.1] | |
If-Modified-Since | http | standard | [RFC7232, Section 3.3] | |
If-None-Match | http | standard | [RFC7232, Section 3.2] | |
If-Range | http | standard | [RFC7233, Section 3.2] | |
If-Schedule-Tag-Match | http | standard | [RFC6638] | |
If-Unmodified-Since | http | standard | [RFC7232, Section 3.4] | |
Importance | [RFC4021] | |||
In-Reply-To | standard | [RFC5322] | ||
Incomplete-Copy | [RFC4021] | |||
Injection-Date | netnews | standard | [RFC5536] | |
Injection-Info | netnews | standard | [RFC5536] | |
Keep-Alive | http | [RFC4229] | ||
Keywords | standard | [RFC5322] | ||
Keywords | netnews | standard | [RFC5536][RFC5322] | |
Label | http | [RFC4229] | ||
Language | [RFC4021] | |||
Last-Modified | http | standard | [RFC7232, Section 2.2] | |
Latest-Delivery-Time | [RFC4021] | |||
Lines | netnews | deprecated | [RFC5536][RFC3977] | |
Link | http | [RFC5988] | ||
List-Archive | [RFC4021] | |||
List-Help | [RFC4021] | |||
List-ID | [RFC4021] | |||
List-Owner | [RFC4021] | |||
List-Post | [RFC4021] | |||
List-Subscribe | [RFC4021] | |||
List-Unsubscribe | perm/list-unsubscribe | [RFC4021] | ||
List-Unsubscribe-Post | standard | [RFC-levine-herkula-oneclick-10] | ||
Location | http | standard | [RFC7231, Section 7.1.2] | |
Lock-Token | http | standard | [RFC4918] | |
Man | http | [RFC4229] | ||
Max-Forwards | http | standard | [RFC7231, Section 5.1.2] | |
Memento-Datetime | http | informational | [RFC7089] | |
Message-Context | [RFC4021] | |||
Message-ID | standard | [RFC5322] | ||
Message-ID | netnews | standard | [RFC5536][RFC5322] | |
Message-Type | [RFC4021] | |||
Meter | http | [RFC4229] | ||
MIME-Version | http | standard | [RFC7231, Appendix A.1] | |
MIME-Version | MIME | [RFC4021] | ||
MMHS-Exempted-Address | [RFC6477][ACP123 Appendix A1.1 and Appendix B.105] | |||
MMHS-Extended-Authorisation-Info | [RFC6477][ACP123 Appendix A1.2 and Appendix B.106] | |||
MMHS-Subject-Indicator-Codes | [RFC6477][ACP123 Appendix A1.3 and Appendix B.107] | |||
MMHS-Handling-Instructions | [RFC6477][ACP123 Appendix A1.4 and Appendix B.108] | |||
MMHS-Message-Instructions | [RFC6477][ACP123 Appendix A1.5 and Appendix B.109] | |||
MMHS-Codress-Message-Indicator | [RFC6477][ACP123 Appendix A1.6 and Appendix B.110] | |||
MMHS-Originator-Reference | [RFC6477][ACP123 Appendix A1.7 and Appendix B.111] | |||
MMHS-Primary-Precedence | [RFC6477][ACP123 Appendix A1.8 and Appendix B.101] | |||
MMHS-Copy-Precedence | [RFC6477][ACP123 Appendix A1.9 and Appendix B.102] | |||
MMHS-Message-Type | [RFC6477][ACP123 Appendix A1.10 and Appendix B.103] | |||
MMHS-Other-Recipients-Indicator-To | [RFC6477][ACP123 Appendix A1.12 and Appendix B.113] | |||
MMHS-Other-Recipients-Indicator-CC | [RFC6477][ACP123 Appendix A1.12 and Appendix B.113] | |||
MMHS-Acp127-Message-Identifier | [RFC6477][ACP123 Appendix A1.14 and Appendix B.116] | |||
MMHS-Originator-PLAD | [RFC6477][ACP123 Appendix A1.15 and Appendix B.117] | |||
MT-Priority | standard | [RFC6758] | ||
Negotiate | http | [RFC4229] | ||
Newsgroups | netnews | standard | [RFC5536] | |
NNTP-Posting-Date | netnews | obsoleted | [RFC5536] | |
NNTP-Posting-Host | netnews | obsoleted | [RFC2980][RFC5536] | |
Obsoletes | [RFC4021] | |||
Opt | http | [RFC4229] | ||
Optional-WWW-Authenticate | http | experimental | [RFC-ietf-httpauth-extension-09, Section 3] | |
Ordering-Type | http | standard | [RFC4229] | |
Organization | informational | [RFC7681] | ||
Organization | netnews | standard | [RFC5536] | |
Origin | http | standard | [RFC6454] | |
Original-Encoded-Information-Types | [RFC4021] | |||
Original-From | standard | [RFC5703] | ||
Original-Message-ID | [RFC4021] | |||
Original-Recipient | perm/original-recipient | standard | [RFC3798][RFC5337] | |
Original-Sender | netnews | standard | [RFC5537] | |
Originator-Return-Address | [RFC4021] | |||
Original-Subject | standard | [RFC5703] | ||
Overwrite | http | standard | [RFC4918] | |
P3P | http | [RFC4229] | ||
Path | netnews | standard | [RFC5536] | |
PEP | http | [RFC4229] | ||
PICS-Label | http | [RFC4229] | ||
PICS-Label | [RFC4021] | |||
Pep-Info | http | [RFC4229] | ||
Position | http | standard | [RFC4229] | |
Posting-Version | netnews | obsoleted | [RFC0850][RFC5536] | |
Pragma | http | standard | [RFC7234, Section 5.4] | |
Prefer | http | standard | [RFC7240] | |
Preference-Applied | http | standard | [RFC7240] | |
Prevent-NonDelivery-Report | [RFC4021] | |||
Priority | [RFC4021] | |||
ProfileObject | http | [RFC4229] | ||
Protocol | http | [RFC4229] | ||
Protocol-Info | http | [RFC4229] | ||
Protocol-Query | http | [RFC4229] | ||
Protocol-Request | http | [RFC4229] | ||
Proxy-Authenticate | http | standard | [RFC7235, Section 4.3] | |
Proxy-Authentication-Info | http | standard | [RFC7615, Section 4] | |
Proxy-Authorization | http | standard | [RFC7235, Section 4.4] | |
Proxy-Features | http | [RFC4229] | ||
Proxy-Instruction | http | [RFC4229] | ||
Public | http | [RFC4229] | ||
Public-Key-Pins | http | standard | [RFC7469] | |
Public-Key-Pins-Report-Only | http | standard | [RFC7469] | |
Range | http | standard | [RFC7233, Section 3.1] | |
Received | standard | [RFC5322][RFC5321] | ||
Received-SPF | standard | [RFC7208] | ||
Redirect-Ref | http | [RFC4437] | ||
References | standard | [RFC5322] | ||
References | netnews | standard | [RFC5536][RFC5322] | |
Referer | http | standard | [RFC7231, Section 5.5.2] | |
Relay-Version | netnews | obsoleted | [RFC0850][RFC5536] | |
Reply-By | [RFC4021] | |||
Reply-To | standard | [RFC5322] | ||
Reply-To | netnews | standard | [RFC5536][RFC5322] | |
Require-Recipient-Valid-Since | standard | [RFC7293] | ||
Resent-Bcc | standard | [RFC5322] | ||
Resent-Cc | standard | [RFC5322] | ||
Resent-Date | standard | [RFC5322] | ||
Resent-From | standard | [RFC5322][RFC6854] | ||
Resent-Message-ID | standard | [RFC5322] | ||
Resent-Reply-To | obsoleted | [RFC5322] | ||
Resent-Sender | standard | [RFC5322][RFC6854] | ||
Resent-To | standard | [RFC5322] | ||
Retry-After | http | standard | [RFC7231, Section 7.1.3] | |
Return-Path | standard | [RFC5322] | ||
Safe | http | [RFC4229] | ||
Schedule-Reply | http | standard | [RFC6638] | |
Schedule-Tag | http | standard | [RFC6638] | |
Sec-WebSocket-Accept | http | standard | [RFC6455] | |
Sec-WebSocket-Extensions | http | standard | [RFC6455] | |
Sec-WebSocket-Key | http | standard | [RFC6455] | |
Sec-WebSocket-Protocol | http | standard | [RFC6455] | |
Sec-WebSocket-Version | http | standard | [RFC6455] | |
Security-Scheme | http | [RFC4229] | ||
See-Also | netnews | obsoleted | [RFC1849][RFC5536] | |
Sender | standard | [RFC5322][RFC6854] | ||
Sender | netnews | standard | [RFC5536][RFC5322] | |
Sensitivity | [RFC4021] | |||
Server | http | standard | [RFC7231, Section 7.4.2] | |
Set-Cookie | http | standard | [RFC6265] | |
Set-Cookie2 | http | obsoleted | [RFC2965][RFC6265] | |
SetProfile | http | [RFC4229] | ||
SLUG | http | standard | [RFC5023] | |
SoapAction | http | [RFC4229] | ||
Solicitation | [RFC3865] | |||
Status-URI | http | [RFC4229] | ||
Strict-Transport-Security | http | standard | [RFC6797] | |
Subject | standard | [RFC5322] | ||
Subject | netnews | standard | [RFC5536][RFC5322] | |
Summary | netnews | standard | [RFC5536] | |
Supersedes | [RFC4021] | |||
Supersedes | netnews | standard | [RFC5536][RFC2156] | |
Surrogate-Capability | http | [RFC4229] | ||
Surrogate-Control | http | [RFC4229] | ||
TCN | http | [RFC4229] | ||
TE | http | standard | [RFC7230, Section 4.3] | |
Timeout | http | standard | [RFC4918] | |
To | standard | [RFC5322] | ||
Topic | http | standard | [RFC8030, Section 5.4] | |
Trailer | http | standard | [RFC7230, Section 4.4] | |
Transfer-Encoding | http | standard | [RFC7230, Section 3.3.1] | |
TTL | http | standard | [RFC8030, Section 5.2] | |
Urgency | http | standard | [RFC8030, Section 5.3] | |
URI | http | [RFC4229] | ||
Upgrade | http | standard | [RFC7230, Section 6.7] | |
User-Agent | http | standard | [RFC7231, Section 5.5.3] | |
User-Agent | netnews | standard | [RFC5536][RFC2616] | |
Variant-Vary | http | [RFC4229] | ||
Vary | http | standard | [RFC7231, Section 7.1.4] | |
VBR-Info | standard | [RFC5518] | ||
Via | http | standard | [RFC7230, Section 5.7.1] | |
WWW-Authenticate | http | standard | [RFC7235, Section 4.1] | |
Want-Digest | http | [RFC4229] | ||
Warning | http | standard | [RFC7234, Section 5.5] | |
X400-Content-Identifier | [RFC4021] | |||
X400-Content-Return | [RFC4021] | |||
X400-Content-Type | [RFC4021] | |||
X400-MTS-Identifier | [RFC4021] | |||
X400-Originator | [RFC4021] | |||
X400-Received | [RFC4021] | |||
X400-Recipients | [RFC4021] | |||
X400-Trace | [RFC4021] | |||
X-Frame-Options | http | informational | [RFC7034] | |
Xref | netnews | standard | [RFC5536] |
Expert Review
Graham Klyne
Registration of a Provisional Message Header Field does not of itself imply any kind of endorsement by the IETF, IANA or any other body.