These indicate the level of support for the given item in each engine. By default, the most recent version of the engine is implied. However, a specific version number can be listed; when this indicates full support, it's the initial version of the engine fully supporting the item.
Elements to present documents in multiple views, which may be independent windows or subwindows. Frame layout is only available in the frameset profiles. All frames are not available in XHTML 1.1 (use generic object elements instead for inline frames).
Elements that specify presentational information. Although not all elements are deprecated, their use is discouraged in favor of stylesheets. Deprecated elements are not available in the strict profiles and XHTML 1.1.
In the early years of the Web, the standards which today are used in most web browsers and web pages were mostly non-existent. Different browsers and HTML editors were being offered by competing vendors such as Netscape and Microsoft, who had competing ideas for how web sites should be constructed. These varying features resulted in web developers coding for specific web browsers, using elements which could often be recognized by only one browser.
These tables list browser engine support for non-standard HTML items.
^<q> does not support nested quotes prior to Gecko 1.8.
^For images, a frame will be added to the object. Other content types are not supported and the element is incorrectly implemented as an ActiveX wrapper. Nested objects fallback mechanism is not supported prior to version 7.
^Prior to Internet Explorer 8.0 (MSHTML 4.0), and in earlier compatibility modes, the innerText is submitted instead of the value attribute.
^MSHTML dropped support for wbr in version 5.0.
^ abcdeSupports preload under the older name autobuffer.
^ abcdGoogle released a WebM component for Media Foundation to allow the playback of WebM files in IE9 through the standard HTML5 <video> tag.[t 45]Xiph.org distributes OpenCodecs package, which amends Google's VP8 decoder with DirectShow-based codecs for Ogg Theora and Ogg Vorbis. VLC media player comes with "Web plugin" that uses VLC for playing multimedia from <video> and <audio> tags, enabling support for all formats VLC supports.
^ abcdefWebKit on macOS previously used QuickTime, and supported whatever formats that does.[w 73] By default, this includes H.264, MP3, AAC and WAV PCM, but not Ogg Theora or Vorbis. These are supported only if installed as third-party codecs, such as XiphQT. However, this relied on QuickTime 7 (not QuickTime X) to play these formats, and since Safari 12 and later versions of WebKit2, Apple officially dropped support for their QuickTime plugin (since it was developed for NPAPI, not HTML5). Google Chrome supports Theora, Vorbis, WebM, and MP3.[w 74] Chromium can be compiled to support anything that FFmpeg supports, and may or may not support patented formats such as H.264 and MP3.[w 75]Origyn Web Browser for MorphOS uses also FFmpeg for playing HTML5 media content.[w 76][w 77]
^ abOn Linux and FreeBSD, Presto 2.5 uses the system version of the GStreamer library, and is able to play any formats supported by GStreamer (including H.264, MP3, AAC and others, if codecs are installed). On other platforms, it only supports Ogg Theora for video; and Ogg Vorbis and WAVE PCM for sound.[p 32]
^Presto 2.0 had partial support for this property.
^ abcOpera 9.5(Presto 2.1) support table claims support for this, but support tables for Presto 2.1.1 up to 2.5 indicate that this property is not supported.
^Prior to version 2.4, Presto only had partial support for this property.
^Gecko had experimental support in version 1.9, with different names.[g 114]
^Beginning in 2007,[p 1] several experimental builds have been released with OggTheora support. Full support for the video element is included in Presto 2.5.[p 2]
^Presto added very limited support for the ECMAScriptAPI related to the audio element in version 2.0 using only the WAVPCM codec, while not implementing the element itself.[p 3] Full support for the audio element with the OggVorbis and WAV codecs is included in Presto 2.5.[p 2]
^The ping attribute is disabled by default, due to privacy concerns.[g 74][g 75]
^The ping attribute is disabled by default, thus needs to be manually enabled by each port
^Currently partially supported in nightly builds for the Linux platform.[g 84]
^WebSocket support was added in Presto 2.7[p 26] but was disabled due to security reasons.[p 27] In Presto 2.11 protocol implementation was updated to version RFC 6455[p 28] which resolved security issue.