Vector Markup Language MHT). Such files retain complete vector information, and can be reopened for editing using other Microsoft applications, such as Microsoft PowerPoint. VML was natively supported by Microsoft's Internet Explorer up to version 9 inline within HTML, using an undefined version of SGML namespaces. Support for VML was dropped in Internet Explorer 10 and subsequent versions. Support for "ink annotations" in Office Open XML files was added to LibreOffice during the 3.7 development cycle. VML is not natively supported by most web browsers. Web browsers such as Mozilla Firefox, Opera, Safari or Google Chrome support SVG instead of VML. Though VML
Adobe Flash enable this option permanently. Both Chrome and Firefox have an option to enable "click to play plugins". Equivalent "Flash blocker" extensions are also available for many popular browsers: Firefox has Flashblock and NoScript, Internet Explorer has Foxie, which contains a number of features, one of them named Flashblock. WebKit-based browsers under macOS, such as Apple's Safari, have ClickToFlash. Firefox (from version 46) rewrites old Flash-only YouTube embed code into YouTube's modern embedded player that is capable of using either HTML5 or Flash. Such embed code is used by non-YouTube sites to embed YouTube's videos, and can still be encountered, for