Network Working GroupJ. Reschke
Updates: 2616 (if approved)July 27, 2010
Intended status: Standards Track
Expires: January 28, 2011

Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)


HTTP/1.1 defines the Content-Disposition  I Response Headerresponse header field, but points out that it is not part of the HTTP/1.1 Standard. This specification takes over the definition and registration of Content-Disposition, as used in HTTP, and clarifies internationalization considerations.

Status of this Memo

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This Internet-Draft will expire on January 28, 2011.

Copyright Notice

Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents ( in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

Editorial Note (To be removed by RFC Editor before publication)

This specification is expected to replace the definition of Content-Disposition in the HTTP/1.1 specification, as currently revised by the IETF HTTPbis working group. See also <>.

Distribution of this document is unlimited. Although this is not a work item of the HTTPbis Working Group, comments should be sent to the Hypertext Transfer Protocol (HTTP) mailing list at, which may be joined by sending a message with subject "subscribe" to

Discussions of the HTTPbis Working Group are archived at <>.

XML versions, latest edits and the issues list for this document are available from <>. A collection of test cases is available at <>.

1. Introduction

HTTP/1.1 defines the Content-Disposition  I response headerresponse header field in Section 19.5.1 of [RFC2616], but points out that  I itis not part of the HTTP/1.1 Standard (Section 15.5):

Content-Disposition is not part of the HTTP standard, but since it is widely implemented, we are documenting its use and risks for implementors.

This specification takes over the definition and registration of Content-Disposition, as used in HTTP. Based on interoperability testing with existing User Agents, it defines a profile of the features defined in the MIME variant ([RFC2183]) of the  I headerheader field, and also clarifies internationalization considerations.

2. Notational Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].

This specification uses the augmented BNF notation defined in Section 2.1 of [RFC2616], including its rules for linear whitespace (LWS).

3.  I Header DefinitionHeader Field Definitions

3.1. Grammar

  content-disposition = "Content-Disposition" ":"
                         disposition-type *( ";" disposition-parm )

  disposition-type    = "inline" | "attachment" | disp-ext-type
                      ; case-insensitive
  disp-ext-type       = token

  disposition-parm    = filename-parm | disp-ext-parm

  filename-parm       = "filename" "=" value
                      | "filename*" "=" ext-value
  disp-ext-parm       = token "=" value
                      | ext-token "=" ext-value
  ext-token           = <the characters in token, followed by "*">

Defined in [RFC2616]:

  token       = <token, defined in [RFC2616], Section 2.2>
  value       = <value, defined in [RFC2616], Section 3.6>

Defined in [draft-reschke-rfc2231-in-http]:

  ext-value   = <ext-value, defined in [draft-reschke-rfc2231-in-http], Section 3.2>

3.2. Disposition Type

If the disposition type matches "attachment" (case-insensitively), the implied suggestion is that the user agent should not display the response, but directly enter a "save response as..." dialog.

On the other hand, if it matches "inline", this implies regular processing. Note that this type may be used when it is desirable to transport filename information for the case of a subsequent, user-initiated, save operation.

Other disposition types SHOULD be handled the same way as "attachment" ([RFC2183], Section 2.8).

3.3. Disposition Parameter: 'Filename'

[rfc.comment.1: Talk about expected behavior, mention security considerations.]

3.4. Disposition Parameter: Extensions

Parameters other  I thenthan "filename" SHOULD be ignored ([RFC2183], Section 2.8).

4. Examples

Direct UA to show "save as" dialog, with a filename of "foo.html":

Content-Disposition: Attachment; filename=foo.html

Direct UA to behave as if the Content-Disposition  I headerheader field wasn't present, but to remember the filename "foo.html" for a subsequent save operation:

Content-Disposition: INLINE; FILENAME= "foo.html"

5. Security Considerations

[csec: Both refer to 2183, and also mention: long filenames, dot and dotdot, absolute paths, mismatches between media type and extension]

6. IANA Considerations

6.1. Registry for Disposition Values and Parameter

 I Section 9 of [RFC2183] defines the registration procedure for new disposition values and parameters.This specification does not introduce any changes to the registration procedures for disposition values and parameters that are defined in Section 9 of [RFC2183].

6.2.  I Header RegistrationHeader Field Registration

This document updates the definition of the Content-Disposition HTTP  I headerheader field in the permanent HTTP  I headerheader field registry (see [RFC3864]).

Header field name:
Applicable protocol:
Author/Change controller:
Specification document:
this specification (Section 3)

7. Acknowledgements

[rfc.comment.2: TBD.]

8. References

8.2. Informative References

Klyne, G., Nottingham, M., and J. Mogul, “Registration Procedures for Message Header Fields”, BCP 90, RFC 3864, September 2004.

Appendix A. Changes from the RFC 2616 Definition

Compared to Section 19.5.1 of [RFC2616], the following normative changes reflecting actual implementations have been made:

Appendix B. Differences compared to RFC 2183

Section 2 of [RFC2183] defines several additional disposition parameters: "creation-date", "modification-date", "quoted-date-time", and "size". These do not appear to be implemented by any user agent, thus have been ommitted from this specification.

Appendix C. Alternative Approaches to Filename Escaping

[rfc.comment.3: Mention: RFC 2047, IE, Safari]


Appendix D. Change Log (to be removed by RFC Editor before publication)

D.1. Since draft-reschke-rfc2183-in-http-00

Adjust terminology ("header" -> "header field"). Update rfc2231-in-http reference.



Author's Address

Julian F. Reschke
greenbytes GmbH
Hafenweg 16
Muenster, NW 48155