Network Working Group                                         P. Hoschka
INTERNET DRAFT                                                       W3C
draft-hoschka-smil-media-type-07.txt                           June 2001

                    The application/smil Media Type

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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   This document specifies the Media Type for version 1 and version 2 of
   the Synchronized Multimedia Integration Language (SMIL 1.0 and SMIL
   2.0). SMIL allows ntegrating a set of independent multimedia objects
   into a synchronized multimedia presentation.

1.  Introduction

   The World Wide Web Consortium has issued specificationss which define
   version 1 [1] and version 2 [2] of  the Synchronized Multimedia
   Integration Language (SMIL 1.0). This memo provides information about
   the application/smil Media Type.

   The definition is based on the RFC3023 defining the use of the
   "application/xml" media type [3]. Before using the "application/smil"
   media type, implementors must thus be familiar with [3].

   RFC 3023 recommends use of the prefix "+xml" for mediatypes that are

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   based on XML. This document does not follow this recommendation,
   since the mediatype "application/smil" is already in widespread news,
   and its definition predates RFC3023 by about two years. This does not
   preclude future registration of "application/smil+xml", should the
   need arise.
2.  Synchronized Multimedia Integration Language

   SMIL allows integrating a set of independent multimedia objects into
   a synchronized multimedia presentation. Using SMIL, an author can

   1.describe the temporal behavior of the presentation
   2.describe the layout of the presentation on a screen
   3.associate hyperlinks with media objects

3.  Registration Information

   Subject: Registration of MIME media type application/smil

   MIME media type name: application

   MIME subtype name: smil

   Required parameters: none

   Optional parameters: charset

   All of the considerations described in RFC3023 also apply to the SMIL
   media type.

Encoding considerations:

All of the considerations described in RFC3023 also apply to the SMIL
media type.

Security considerations:

   SMIL documents contain a construct that allows "infinite loops".
   This is indispensible for a multimedia format. However, SMIL clients
   should foresee provisions such as a "stop" button that lets users
   interrupt such an "infinite loop".

   As with HTML, SMIL documents contain links to other media
   (images,sounds, videos, text, ...) and those links are typically
   followed automatically by software, resulting in the transfer of
   files without the explicit request of the user for each one. The
   security considerations of each linked file are those of the
   individual registered types.

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   The SMIL language contains "switch" elements. SMIL provides no
   mechanism that assures the media objects contained in a "switch"
   element provide equivalent information. An author, knowing that one
   SMIL player will display one alternative of a "switch" and another
   will display a different part, can put different information in the
   two parts. While there are legitimate use cases for this, this also
   gives rise to a security consideration:  The author can fool viewers
   into thinking that the same information was displayed when in fact it
   was not.

   In addition, all of the security considerations of RFC3023 also apply
   to SMIL.

Interoperability considerations:

   SMIL documents contain links to other media objects. The SMIL player
   must be able to decode the media types of these media in order to
   display the whole document. To increase interoperability, SMIL has
   provisions for including alternate versions of a media object in a

Published specification: see [1] and [2]

Applications which use this media type:

SMIL players and editors

Additional information:

Semantics of fragment identifiers in URIs: The SMIL media type allows to
append a fragment identifier to a URI pointing to a SMIL resource (e.g.  The semantics of fragment
identifers for SMIL resources are defined in [1].

Magic number(s): none

   All of the considerations described in RFC3023 also apply to the SMIL
   media type.

File extension(s): .smil, .smi, .sml

NOTE: On the Windows operating system and the Macintosh
platform, the ".smi" extension is
used by other formats. To avoid conflicts, it is thus
strongly recommended not to use the extension ".smi" for storing
SMIL files on these platforms.

Macintosh File Type Code(s): "TEXT", ".SMI", "SMIL", "PNRM"

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Object Identifier(s) or OID(s): none

Person & email address to contact for further information:

The author of this memo.

Intended usage: COMMON

Author/Change controller:

   The SMIL 1.0 and SMIL 2.0 specifications are a work product of the
   World Wide Web Consortium's SYMM Working Group.

   The W3C has change control over the SMIL 1.0 specification.

5.  References

   [1]  "Synchronized Multimedia Integration Language (SMIL) 1.0
        Specification", W3C Recommendation REC-smil-19980615,, July 1998.
   [2] "Synchronized Multimedia Integration Language (SMIL) 2.0
        Specification", W3C Proposed Recommendation
        June 2001.
   [3]  M. Murata, S. St.Laurent, D. Kohn E. "XML Media Types", RFC 3023,
        UC Irvine IBM Tokyo Research Laboratory,, Skymoon Ventures,
        January 2001.

6.  Author's Address

   Philipp Hoschka
   2004, route des Lucioles - B.P. 93
   06902 Sophia Antipolis Cedex

   Phone: +33 (0)492387984
   Fax:+33 (0)493657765

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