This element holds a binding's <method> and <property> elements that, as a whole, make up a binding's behavior. The optional implements attribute can hold a list of comma-separated XPCOM interfaces that are used by the implementation's methods and properties. The optional type attribute represents the scripting language to be used. This attribute defaults to JavaScript, the only implemented language that scripts Mozilla's XPFE.
<implementation type="application/x-javascript" implements="nsIAccessibleProvider">
...
</implementation>