Disposed

It is triggered after the UI view has been disposed.

It can be used, for example, to dispose the objects retained in the DOM, unsubscribe from events to which you have subscribed in the initialization event.

Item versus DatasourceCurrent

This rule is not tied to a particular item so it does not offer an Item property.

To know more on the difference between the Item and DatasourceCurrent properties in an UI view event rule, you can check this article.