Appendix G: Media Type registration for image/svg+xml

This appendix is normative.

G.1 Introduction

This appendix registers a new MIME media type, "image/svg+xml" in conformance with RegMedia and W3CRegMedia.

G.2 Registration of Media Type image/svg+xml

MIME media type name:

image

MIME subtype name:

svg+xml

Required parameters:

None.

Optional parameters:

None

The encoding of an SVG document is determined by the XML encoding declaration. This has identical semantics to the application/xml media type in the case where the charset parameter is omitted, as specified in RFC3023 sections 8.9, 8.10 and 8.11.

Encoding considerations:

Same as for application/xml. See RFC3023 , section 3.2.

Restrictions on usage:

None

Security considerations:

As with other XML types and as noted in RFC3023 section 10, repeated expansion of maliciously constructed XML entities can be used to consume large amounts of memory, which may cause XML processors in constrained environments to fail.

SVG documents may be transmitted in compressed form using gzip compression. For systems which employ MIME-like mechanisms, such as HTTP, this is indicated by the Content-Transfer-Encoding header; for systems which do not, such as direct filesystem access, this is indicated by the filename extension and by the Macintosh File Type Codes. In addition, gzip compressed content is readily recognised by the initial byte sequence as described in RFC1952 section 2.3.1.

Several SVG elements may cause arbitrary URIs to be referenced. In this case, the security issues of RFC2396, section 7, should be considered.

In common with HTML, SVG documents may reference external media such as images, audio, video, style sheets, and scripting languages. Scripting languages are executable content. In this case, the security considerations in the Media Type registrations for those formats apply.

In addition, because of the extensibility features for SVG and of XML in general, it is possible that "image/svg+xml" may describe content that has security implications beyond those described here. However, if the processor follows only the normative semantics of this specification, this content will be outside the SVG namespace and will be ignored. Only in the case where the processor recognizes and processes the additional content, or where further processing of that content is dispatched to other processors, would security issues potentially arise. And in that case, they would fall outside the domain of this registration document.

Interoperability considerations:

This specification describes processing semantics that dictate behavior that must be followed when dealing with, among other things, unrecognized elements and attributes, both in the SVG namespace and in other namespaces.

Because SVG is extensible, conformant "image/svg+xml" processors must expect that content received is well-formed XML, but it cannot be guaranteed that the content is valid to a particular DTD or Schema or that the processor will recognize all of the elements and attributes in the document.

SVG has a published Test Suite and associated implementation report showing which implementations passed which tests at the time of the report. This information is periodically updated as new tests are added or as implementations improve.

Published specification:

This media type registration is extracted from Appendix G of the SVG 1.2 specification.

Additional information:

Person & email address to contact for further information:

Dean Jackson, (dean@w3.org).

Intended usage:

COMMON

Author/Change controller:

The SVG specification is a work product of the World Wide Web Consortium's SVG Working Group. The W3C has change control over these specifications.