Web specifications supported in Opera 9.5


This page applies to Opera 9.5 on FreeBSD, Mac, Linux, Solaris and Windows, as well as Opera Mobile. For Opera, version 9, see Specifications for Opera 9.

This Web document has been transformed into portable document format (.pdf) for your convenience. Note that a .pdf reader installed in your computer is required to view it.

HTML and XHTML support

Complete table of HTML, XHTML and WML support

HTML 4.01, XHTML 1.0 and XHTML 1.1

Opera supports HTML 4.01, XHTML 1.0 and XHTML 1.1 with these exceptions:

  • The longdesc attribute of the img element is not supported.
  • Event attributes are not supported for the option element.
  • The col width attribute does not support multilengths.
  • The object standby and declare attributes are not supported.
  • The table cell attributes char and charoff are not supported.
  • The defer="" attribute on script elements is not supported.
  • The basefont element is not supported.
  • Ruby annotations are not supported.

Opera uses the HTML parser for text/html resources and the XML parser for resources with a XML MIME-type such as application/xhtml+xml. Please note that namespaces are not supported for text/html; this practice was discontinued with the release of Opera 9.

HTML 5 (a draft in development)

Opera 9.5 adds support for the next version of HTML - HTML 5. Note that HTML 5 is a work in progress, thus changes to the draft specification may be made at any time. Respectively, Opera considers its implementations for HTML 5 experimental until its specification has stabilized. Support is provided for the following:

  • <canvas> element/API
  • contenteditable attribute
  • designMode DOM attribute
  • innerHTML
  • getElementsByClassName
  • embed element
  • Audio object
  • Cross-document messaging
  • Server-sent DOM events

Web Forms 2.0

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


Opera supports XHTML Basic with the following exceptions:

  • The object standby, declare attributes are not supported.
  • The inputmode attribute is supported; however,
    • its implementation is platform-dependant
    • it is not enabled by default
    • it is not in the Opera 9.5 Desktop version

OMA XHTML Mobile Profile

Opera supports the XHTML Mobile Profile 1.0 and 1.1 and extensions to XHTML Basic with no exceptions.

XHTML+Voice (X+V)

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

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:

  • the columns attribute
  • the input formatting code <lang:class>
  • the wml:getvar element

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:

  • The namespace-alias element is not supported.
  • Opera does not support XSL-FO.


Opera supports the xml:id attribute.

XML namespaces

Opera fully supports XML namespaces.

XML Events

Opera supports XML Events and it is used in SVG and X+V.

  • HTML script and VoiceXML form can be handlers for XML Events.


Opera supports the XML <svg:handler> element. This element only executes its content when called from an XML Event listener.


Opera allows CSS style sheets and XSLT transformation sheets to be linked to XML with an XML Processing instruction according to

  • the W3C Recommendation "Associating Style Sheets with XML Documents"
  • the HTTP Link: header proposed for standardization in the IETF
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 or SVG, Opera 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.

MathML Support

MathML for CSS profile

Opera 9.5 supports the current working draft of the MathML for CSS profile with the following exceptions:

  • Radicals and some fences do not inherit text color from document.
  • White space characters between token elements (mi, mn, mo, ms, mspace, mtext) are not discarded.
  • class and style attributes are not supported.

The following tabular data table contains specific elements/attributes included in the profile:

MathML for CSS profile elements handled by Opera 9.5
Element Supported Attribute Values Default
maction Yes actiontype (tooltip) #REQUIRED
math Yes display (block | inline) inline
xmlns http://www.w3.org/1998/Math/MathML #REQUIRED
menclose Yes notation (bottom | box | left | right | top | horizontalstrike) #REQUIRED
merror Yes      
mfenced Yes open CDATA (
close CDATA )
mfrac Yes linethickness (0 | 1 | 2 | medium | thick) medium
mi Yes mathvariant (normal | bold | italic | bold-italic | sans-serif | bold-sans-serif | sans-serif-italic | sans-serif-bold-italic | monospace) italic
mn Yes mathvariant (normal | bold | italic | bold-italic | sans-serif | bold-sans-serif | sans-serif-italic | sans-serif-bold-italic | monospace) normal
mo Yes mathvariant (normal | bold | italic | bold-italic | sans-serif | bold-sans-serif | sans-serif-italic | sans-serif-bold-italic | monospace) normal
largeop (true | false) false
separator (true | false) false
form (prefix | infix | postfix) context dependent
mover Yes      
mphantom Yes      
mroot Yes      
mrow Yes      
ms Yes mathvariant (normal | bold | italic | bold-italic | sans-serif | bold-sans-serif | sans-serif-italic | sans-serif-bold-italic | monospace) normal
lquote CDATA "
rquote CDATA "
mspace Yes linebreak (auto | newline | goodbreak) auto
msqrt Yes      
msub Yes      
msubsup Yes      
msup Yes      
mtable Yes frame (none | solid | dashed) none
rowalign (top | bottom | center | baseline) baseline
columnalign (left | center | right) center
rowlines (none | solid | dashed) none
columnlines (none | solid | dashed) none
mtd Yes rowalign (top | bottom | center | baseline) baseline
columnalign (left | center | right) center
mtext Yes mathvariant (normal | bold | italic | bold-italic | sans-serif | bold-sans-serif | sans-serif-italic | sans-serif-bold-italic | monospace) normal
mtr Yes rowalign (top | bottom | center | baseline) baseline
columnalign (left | center | right) center
munder Yes      
munderover Yes      

CSS support

Table of CSS support

CSS Level 1

Opera supports all of CSS1.

CSS Level 2

Opera supports CSS2 with the exception of these

  • properties:
    • font-size-adjust
    • font-stretch
    • marker-offset
    • marks
  • list style types:
    • cjk-ideographic
    • hebrew
    • hiragana
    • hiragana-iroha
    • katakana
    • katakana-iroha
  • property/value combinations:
    • display: marker
    • text-align: <string>
    • visibility: collapse
  • named pages (as described in section 13.3.2)
  • the @font-face construct
  • URI values for the cursor property

CSS Level 2 Revision 1

CSS 2.1 is currently a W3C Candidate Recommendation.

  • Its compliance is measured against the latest version, but the final recommendation may differ.
  • Opera supports CSS2.1 with the exception of:
    • the visibility: collapse property value

CSS3 - proposed properties supported by Opera

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

  • selectors level 3
  • the HSL color model
  • partial support for Media Queries
  • content applicable on all elements, not just on the :before and :after pseudo-elements
  • box-sizing
  • opacity
  • overflow-x
  • overflow-y
  • text-shadow, including multiple shadows
  • outline-offset
  • currentColor
  • -o-background-size
  • -o-table-baseline
  • -o-text-overflow
  • nav-up, nav-right, nav-down, nav-left

CSS Mobile profile

Opera fully supports the CSS Mobile Profile 1.0. Note that the CSS Mobile Profile 2.0 is in draft stage and coinsidered a work in progress. For your guide, Opera support for the 2.0 Profile will be added to this document as it occurs.


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

WAI-ARIA support

Opera's participation

WAI-ARIA is a proposal/work in progress. Opera participates in this working group which will ultimately release the WAI-ARIA specification. Please see the WAI-ARIA Working Draft for details.

Opera 9.5 supports parsing WAI-ARIA in HTML with the attributes in a null namespace ("in no namespace"), as per the latest decisions on WAI-ARIA at the time Opera 9.5 was released. This support is experimental, while the WAI-ARIA standard stabilizes.

Widgets support

Opera supports widgets and accordingly has produced the Opera Widgets SDK.

  • 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.

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.

ECMA-262 2 and 3

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

ECMAScript 3.x and 4

Opera is actively participating in ECMA TC39 which is involved with developing successors to the current specification. Opera will support future editions of the language as consensus is reached and the specs become finalized.

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
  • 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 when it becomes a recommendation.

DOM 2 Style

Opera supports DOM 2 Style with some exceptions.

  • The CSS object model is under development in order to replace the existing DOM 2 style specification. Opera actively participates in this work, and we expect to support fully the new object model.

DOM 2 Range

Opera supports the DOM 2 Range.

DOM 2 Traversal

Opera supports DOM 2 Traversal, with some exceptions.

DOM 3 Element Traversal specification (Working Draft)

Opera supports the Element Traversal specification (Working Draft).

  • The ElementTraversal interface allows script navigation of the elements of a DOM tree, excluding all other nodes in the DOM, such as text nodes.
  • It also provides an attribute to expose the number of child elements of an element.

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.


Note: see the preceding DOM SVG table and also the SVG section in following Graphics support topic.

Opera supports DOM SVG with the following version 1.1 exceptions:

  • SVGAltGlyphDefElement
  • SVGAltGlyphElement
  • SVGAltGlyphItemElement
  • SVGCSSRule
  • SVGColorProfileElement
  • SVGColorProfileRule
  • vSVGCursorElement
  • SVGEvent
  • SVGExternalResourcesRequired
  • SVGGlyphRefElement
  • SVGICCColor (no ICC color support)
  • SVGLangSpace
  • SVGRenderingIntent
  • SVGViewSpec
  • SVGZoomEvent

XMLHttpRequest (XHR)

Opera actively participates in the W3C Web Applications Working Group, which is repsonsible for XMLHttpRequest specification. The XMLHttpRequest specification is in draft status as of the release date of Opera 9.5. We expect to support it fully when it becomes a recommendation.


Opera supports the <canvas> element specification, which is currently a work in progress.

Networking protocols support


Opera has full support for HTTP 1.0 and HTTP 1.1. Highlights include the following

  • Persistent connections (multiple request/response through one connection)
  • Cache-Control
    • no-cache (always check for fresh document)
    • no-store (do not save to disk)
    • must-revalidate (only for HTTPS pages, which indicates that the document should be revalidated during history navigation)
  • Basic Authentication (passwords)
    • Supports Digest Authentication, excepting integrity check on body.
  • Resume download, provided the server supports it
  • SSL, TLS support (also through proxy/firewall)
  • Proxy for HTTP, FTP, Gopher and WAIS
  • HTTP upload of files is supported.


Opera supports 128 and 256 bit encryption (RSA, DSA and DH key exchange methods) for the Secure Sockets Layer (SSL) version 3, and the successor Transport Layer Security (TLS) 1.0 and 1.1.

  • This is supported for HTTP (Web), IRC (chat), NNTP (news), POP and SMTP (e-mail).
  • Note: SSL 2 is obsolete and no longer supported.
  • Support for generating private keys and submitting certificate requests.
  • Support for Extended Validation (EV).
    • An indicator (green bar) for EV certificates acts as an identifier in the Address Bar of the browser.

Opera supports the same preceding encryption standards for IRC.


Opera supports the preceding encryption standards for Mail. This includes:

  • support for mail (IMAP/POP, SMTP) and mail encoded with MIME, HTML, SVG or RFC2822 (the current mail standard).

Opera supports NNTP, along with RSS and Atom feeds.

  • A simple online newsreader with support for encrypted newsservers and newsservers with passwords is provided, which supports decoding of single article attachments, MIME or unencoded.

Text and internationalization support

Unicode character set 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 supported by Opera, such as:
      • Windows 95®
      • Windows 98®
  • For information on available fonts, see Unicode fonts for Windows computers.

Opera 9.5 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 and so forth.

Support for bi-directional text

Opera supports bi-directional text as described in Unicode, HTML, and CSS.

Legacy encoding support

Although Opera works with the Unicode character set and its character encodings of UTF-16 and UTF-8, most text on the Internet is encoded in legacy encodings.

Legacy encodings supported by Opera
Encoding Category Comments
ISO 8859-1 Latin
ISO 8859-2 Latin Used in Eastern Europe
ISO 8859-3 Latin Rare
ISO 8859-4 Latin Sami and Baltic country
ISO 8859-9 Latin Turkish
ISO 8859-10 Latin Inuit, Sami, and Icelandic
ISO 8859-13 Latin Rare
ISO 8859-14 Latin Celtic
ISO 8859-15 Latin Intended to supersede 8859-1
Windows-1250 Latin Used in Eastern Europe
Windows-1252 Latin
Windows-1254 Latin Turkish
Windows-1257 Latin Baltic
Windows-1258 Latin Vietnamese
VISCII Latin Vietnamese
IBM 866 Cyrillic
ISO 8859-5 Cyrillic
koi8-r Cyrillic
koi8-u Cyrillic Ukrainian version of koi8-r
Windows-1251 Cyrillic
ISO 8859-6 Arabic
Windows-1256 Arabic
ISO 8859-7 Greek
Windows-1253 Greek
ISO 8859-8 Hebrew
Windows-1255 Hebrew
ISO 8859-11 Thai Also known as TIS-620
Windows-874 Thai Extension of ISO 8859-11
utf-8 Unicode
utf-16 Unicode
Shift-JIS Japanese
ISO-2022-JP Japanese
EUC-JP Japanese
Big 5 Chinese
EUC-CN Chinese Also erroneously known as GB 2312
HZ-GB-2312 Chinese Primarily used in e-mail
EUC-TW Chinese
GBK Chinese EUC-CN extension
EUC-KR Korean

Because many pages are mislabeled, Opera provides various options to find the encoding:

In this mode, Opera will attempt to detect the encoding used by the Web page.
Writing script auto-detect
In this mode, the user can tell that this is a Japanese or Chinese Web page but that the encoding is unknown. Opera will then analyze the text in the Web 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 Web page and transport protocol claims is the encoding for the Web page.

Graphics support

Raster Graphics

Opera fully supports:

  • GIF89a
  • JPEG
  • BMP
  • ICO
  • WBMP
  • PNG including alpha channel (degrees of transparency) and gamma support (device independent colors)
  • APNG (Animated PNG images)

Scalable Vector Graphics (SVG)


There is support for listening to any event in the SVG module. Some events are not sent by core, for example: activate.

  • SVG 1.1 doesn't specify a key-event set, and thus the attributes onkeyup, onkeydown and onkeypress do not register a corresponding event listener for those events.
  • In Opera it is possible to install listeners for key-events with DOM, for example: element.addEventListener('keydown', keyhandler-function, false).
  • If key-events are used it is vital to use evt.preventDefault() to prevent any key-event that should be handled only by the script from escaping upwards to the UI which may be listening for shortcut keys.

Opera supports the following SVG inclusion types:

  • html:object element
  • html:iframe element
  • html:embed element
  • html:img element
  • in CSS:
    • background-image
    • list-style-image

Some content may fail to render if sent with the wrong MIME-type or if the namespace declarations are missing.

  • The correct MIME-type for SVG is image/svg+xml.
  • The namespaces to open are svg: http://www.w3.org/2000/svg and xlink: http://www.w3.org/1999/xlink.
  • For CSS it should be noted that you must specify length values with units. For example:
    • font-size: 12; in CSS will mean the value is invalid, and thus it will be ignored.
    • This applies to all 'style' elements, 'style' attributes and external style sheets.
    • The CSS content property can also embed SVG.

SVG is output as a bitmap image to the printer.

  • The output is not sent in vector format, thus the clarity of the image may be blurred.

Appendix A: Abbreviations and acronyms used in this document

Abbreviations and acronyms used in this document
Abbreviation/Acronym Description
APNG Animated Portable Network Graphics
BMP Bitmap graphic filename extension
CJK Chinese Japanese Korean (unicode UTF-8 encoding standard)
CSS Cascading Style Sheets
DCC Digital Content Creation
DOM Document Object Model
ECMA European Computer Manufacturers Association
EUC-KR Korean Character Encoding Standard
EV Extended Validation
FTP File Transfer Protocol
GIF Graphic Interchange Format filename extension
HTML Hypertext Markup Language
HTTP Hypertext Transfer Protocol
ICO Icon graphic filename extension
IMAP Internet Message Access Protocol
IRC Internet Relay Chat
ISO International Organization for Standardization
JPEG Joint Photographic Experts Group graphic filename extension
MIME Multimedia Internet Message Extensions
NNTP Network News Transport Protocol
OMA Open Mobile Alliance
POP Post Office Protocol
PNG Portable Network Graphics
RSA Rivest, Shamir and Adleman (public key encryption technology)
RSS Really Simple Syndication
SDK Software Development Kit
SHIFT-JIS Shift Japanese Industrial Standard (character encoding system)
SMTP Simple Mail Transfer Protocol
SSL Secure Sockets Layer
SVG Scalable Vector Graphics
TLS Transport Layer Security
UTF Unicode Transformation Format
WAI-ARIA Web Accessibility Initiative-Accessible Rich Internet Applications
WAIS Wide Area Information Server
WAP Wireless Application Protocol
WBMP Wireless Bitmap (WAP) graphic filename extension
WML Wireless Application Protocol Markup Language
XHTML Extensible Hypertext Markup Language
XML Extensible Markup Language
XPath XML Path Language
XSL-FO Extensible Style sheet Language Format Objects
XSLT Extensible Style sheet Language Transformation


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