This add-on adds three items to the contextual menu that appears when you click on a MathML formula: - "Copy MathML Formula" will copy the MathML source as text and html. This means that you can paste the MathML source into any text editor and the MathML formula into any standard-compliant HTML5 editor. For example, you can paste the MathML formula into any Gecko editor (e.g. Thunderbird, Seamonkey, KompoZer, BlueGriffon etc) or any Web page with a contenteditable section (e.g. CKEditor, used on MDN). - "Copy Annotation" is a submenu to copy any annotation associated to a MathML formula via the semantics element. This includes in particular various TeX annotations. Try to copy equations from the Instiki Sandbox and paste them in your favorite text editor or this HTML5 editor.