== Packaging ==
Extensions are packaged as standard Zip files, but with <code>.xpi</code> extensions. In the future, we're planning to use move towards whatever the <code>.zip</code> extension insteadW3C WG recommends.
The <code>manifest.json</code> file supports the following directives, in addition to the directives supported by Blink: <blockquote><pre>"applications": { "gecko": { "id": "{the-addon-id}", "strict_min_version": "40.0.0", "strict_max_version": "50.*" "update_url": "https://foo/bar" }}</pre></blockquote> Both version fields are Gecko versions, and allow extension to support any application built on that version of Gecko. In the case of Firefox, they correspond to the Firefox release version. The <code>update_url</code> field may point to an [https://developer.mozilla.org/en-US/docs/Extension_Versioning,_Update_and_Compatibility#Update_RDF_Format RDF update manifest] to allow automatic updates. In the future, we hope to make all of these properties optional (which will require generating a unique ID upon installation or upload to addons.mozilla.org). See https://developer.chrome.com/extensions/manifest for a complete list of manifest directives. Of these, we currently support the following: * name* version* description* content_scripts* permissions* web_accessible_resources* background* browser_action* default_locale
== API support status ==
