Web Specifications Supported in Opera 9

This page applies to the FreeBSD, Mac, Linux, Solaris, Symbian and Windows version 9. Opera 9 for Nintendo Wii is documented separately. For Opera version 8, see Specifications for Opera 8.

Opera HTML and XHTML support

HTML 4.01

Opera supports HTML 4.01 with these exceptions:

Web Forms 2.0

Opera has experimental support for Web Forms 2.0. Web Forms 2.0 is a work in progress.

XHTML 1.0 and XHTML Modularization

There are two "modes" of XHTML support, one where the document has the text/html content type and the other where it has one of text/xml, application/xml or application/xhtml+xml. In the first case the document is handled as any other HTML document (giving de facto support for XHTML 1.0, XHTML Basic and XHTML 1.1). In the second case XHTML will be treated as XML with predetermined functionality for HTML elements and attributes. Opera supports both modes.

XHTML 1.1 support

Opera supports XHTML 1.1 with these exceptions:


Opera supports XHTML Basic with the following exception:

OMA XHTML Mobile Profile

Opera supports the XHTML Mobile Profile 1.0 and 1.1 extensions to XHTML Basic with no exceptions. It supports 1.2 with the exception of the declare attribute of object.

XHTML+Voice (X+V) support

With the IBM Voice component Opera fully supports the XHTML+Voice profile 1.2 (and the Mobile Profile subset). The support of X+V includes support of CSS3 Speech (with an -xv- prefix as this module is under preparation). X+V needs to be served as an XML media type (application/xml, application/xhtml+xml, application/x-xhtml+voice+xml) for XML Events to take effect. For more information see the X+V developer documentation.

WML 1.3 and 2.0 support

Wireless Markup Language versions 1.0 to 1.3, while based on an HTML subset, must be considered a separate markup language for most practical purposes. WML 2.0 can better be considered an extension of XHTML Basic with WML 1.3 features.

Opera supports WML 1.3 and 2.0 with the following exceptions:

Widget support

Opera supports HTML Widgets. Widgets are Client Side Web Applications that run on the user's Desktop, Mobile or other device. The Opera Widgets specification was submitted to the W3C and Widgets 1.0 is currently a W3C working draft.

XML support

Opera can parse and display XML documents. Opera can be both a validating and non-validating processor.

Documents with Content-type "text/xml", "application/xml" or with a subtype ending on "+xml" will be treated as an XML document. If a Content-type is not available, the ".xml" file extension will also make the document be treated as XML. Opera does not use US-ASCII as the default character set for text/xml, but otherwise follows RFC3023. We recommend using application/xml instead of text/xml or use explicit character set declaration.

XSLT, XPath, and XSL-FO

Opera supports XSLT 1.0 and XPath 1.0 with the following exceptions:

In addition the exsl:node-set() function is supported.

Opera does not support XSL Formatting Objects.

XML namespaces and XML ID

Opera fully supports XML namespaces.

Namespace support for text/html has been discontinued with Opera 9.

Opera supports the xml:id attribute.

XML Events

Opera supports XML Events and it is used in X+V. HTML script and VoiceXML form can be handlers for XML Events.

CSS support

Table of CSS support

CSS Level 1

Opera supports all of CSS1.

CSS Level 2

Opera supports all of CSS2 with the exception of:

CSS Level 2 Revision 1

CSS 2.1 is currently a W3C Candidate Recommendation, compliance is measured against the latest version, but the final Recommendation may differ.

Opera supports all of CSS2.1 with the exception of:

CSS Mobile profile

Opera fully supports CSS Mobile profile.


WAP CSS is an extension of CSS Mobile Profile. Opera fully supports WCSS versions 1.0 and 1.1.

Proposed CSS 3 properties supported by Opera

Note that these properties are at an early stage of development, they may be changed or removed from the specifications at any time. Use them as experimental.

Opera uses CSS-like properties to attach information to XML elements that cannot otherwise be represented. Three extension properties have been implemented to allow hyperlinks and images to be included in XML documents. Most often it's better for authors to use XHTML - rather than the properties described below - to represent document semantics, but they are described here for reference.

CSS Extensions for XML
Values:none | attr(<attribute-name>)
Description:This property sets the value of the "link" variable which can later be used to generate a link through the "-o-link-source" property.
Values:none | current | next
Description:This property sets the element to be a source anchor and, if so, declares which value of the '-o-link' variable that should be used: the current or the next.

-o-replace is discontinued. It is expected to be replaced by an equivalent CSS3 mechanism.


In order to display an XML document, a CSS style sheet should be present. Authors can attach style sheets to their XML documents through a processing instruction. Here is a simple example:

<?XML version="1.0"?>
<?xml-stylesheet href="shakespeare.css" type="text/css"?>

If no style sheet is present and the page is not namespaced to HTML, Opera 9 will use the initial values on all CSS properties to display the document. All elements will be inline, and all text will be rendered in the same font.

ECMAScript support

ECMAScript is the standardized version of JavaScript Core. It is being standardized through the ECMA standards body. ECMAScript does not include browser and document related objects.

Opera supports the entire ECMA-262 2ed and 3ed standards, with no exceptions. They are more or less aligned with JavaScript 1.3/1.5 Core.

DOM support

DOM 2 Core

Opera has full support for the Fundamental interfaces of DOM 2 Core, with minor exceptions. Opera does not support these Extended interfaces: Notation, Entity, and EntityReference.


Opera has full support for DOM 2 HTML, with minor exceptions corresponding to HTML support exceptions.

DOM 2 Events

Opera 9 has full support of DOM 2 Events with no exceptions. The work on DOM 3 Events has restarted at the W3C, we expect to have no exceptions there when it becomes a recommendation.

DOM 2 Style

Opera supports DOM 2 Style with some exceptions. This module is under development in the W3C and we expect to fully support the updated version.

DOM 2 Range

Opera supports DOM 2 Range.

DOM 2 Traversal

Opera supports DOM 2 Traversal, with some exceptions.

DOM 3 Load and Save

Opera supports Load and Save, with some exceptions.

DOM 3 XPath

Opera supports DOM 3 XPath, with the same exceptions as with XSLT. This DOM specification is currently a W3C note.


XMLHTTPRequest is a work in progress, we expect to fully support it when it becomes a recommendation


Opera has an experimental Canvas support. The Canvas specification is a work in progress.

Networking protocols support

Opera has full support for HTTP 1.0 and HTTP 1.1. Here are some highlights:

Encryption: 128 bit encryption (RSA key exchange only) for the Secure Sockets Layer (SSL) versions 2 and 3, and the successor Transport Layer Security (TLS) 1.0 and 1.1. SSL 2 is obsolete and not supported by default. This is supported for HTTP (web), NNTP (news), POP and SMTP (e-mail). Support for generating private keys and submitting certificate requests.

News: simple online newsreader with support for encrypted newsservers and newsserver with passwords. Can decode single article attachments, MIME or uuencoded.

FTP including resume download is supported.

It is possible to download to file for both FTP and HTTP.

Text and internationalization

Unicode support in Opera

Opera can work with all the characters in the Unicode specification. All text communicated to Opera from the network is converted into Unicode.

In order for Opera to render Unicode characters, the needed glyphs have to be available in the fonts on your system. This might be a problem for older Windows systems. For information on available fonts, see Unicode fonts for Windows computers.

Opera 9 implements the following writing system related functionality:

Needed in order to display characters that the current font does not include.
Needed in order to break scripts written without spaces, such as Chinese, Korean, and Japanese.

Opera relies on the operating system to perform:

character shaping
Contextual glyph selection, ligature forming, character stacking, combining character support etc.

Legacy encoding support

Although Opera works with Unicode encodings (UTF-16 and UTF-8), most text on the Internet is encoded in legacy encodings, for instance ISO 8859-1, Windows-1251, Shift-JIS, EUC-KR. Opera handles this by detecting the character encoding used, and converting it to UTF-16. The user has three options for how to handle these pages.

In this mode Opera will attempt to detect the encoding used by the page. If the transport protocol provides an encoding name, that is used. If not, Opera will look at the page for a charset declaration. If this is missing, Opera will attempt to auto-detect the encoding, using the domain name to see if the script is a CJK script, and if so which one. Opera can also auto-detect UTF-8.
Writing script auto-detect
In this mode the user can tell that this is a Japanese or Chinese page, but that the encoding is unknown. Opera will then analyze the text in the page to determine which encoding is used.
Encoding override
In this mode the user selects an encoding. This encoding will be used by Opera, regardless of what the page and transport protocol claims is the encoding for the page.

This table shows all the legacy encodings Opera supports in addition to Unicode:

Legacy Encodings
ISO 8859-1Latin
ISO 8859-2LatinUsed in Eastern Europe
ISO 8859-3LatinRare
ISO 8859-4LatinSami and Baltic country
ISO 8859-9LatinTurkish
ISO 8859-10LatinInuit, Sami, and Icelandic
ISO 8859-13LatinRare
ISO 8859-14LatinCeltic
ISO 8859-15LatinIntended to supersede 8859-1
Windows-1250LatinUsed in Eastern Europe
IBM 866Cyrillic
ISO 8859-5Cyrillic
koi8-uCyrillicUkrainian version of koi8-r
ISO 8859-6Arabic
ISO 8859-7Greek
ISO 8859-8Hebrew
ISO 8859-11ThaiAlso known as TIS-620
Windows-874ThaiExtension of ISO 8859-11
Big 5Chinese
EUC-CNChineseAlso erroneously known as GB 2312
HZ-GB-2312ChinesePrimarily used in e-mail
GBKChineseEUC-CN extension

Support for bidirectional text

Opera supports bidirectional text as described in Unicode, HTML, and CSS.

Graphics support

Scalable Vector Graphics (SVG)

Complete table of SVG support

Opera supports a superset of SVG 1.1 Basic and SVG 1.1 Tiny with some exceptions. This maps to a partial support of SVG 1.1.

Event listening to any event is supported, but some events are not sent by the application, for example focusin, focusout and activate. The Adobe-specific events keyup and keydown are not supported. Fonts are supported, including font-family, but if there is a missing glyph in the selected font a platform-defined fallback will be used instead of picking that glyph from the next font in line in the font-family property.

SVG can be used in object, embed, and iframe in HTML and as stand-alone documents. It is not supported for img elements or in CSS property values (e.g. background-image). An SVG image element can contain any supported raster graphics, but not another SVG image. References to external resources are not supported.

SVG images are printed as bitmap images.

SVG is processed as XML and the same rules for well-formedness and namespaces apply. Opera also follows the SVG conformance rules that requires processing to stop if any unknown feature is encountered.


These features are particularly processor expensive and should be used with care when targetting machines with slower processors: filters, transparency layers (group opacity), and masks.

Raster Graphics

Opera fully supports GIF89a, JPEG, BMP, ICO, WBMP, and has full support for PNG including alpha channel (degrees of transparency) and gamma support (device independent colors).


Opera Help

Need help? Hit F1 anytime while using Opera to access our online help files, or go here.