[oXygen-user] Update element on save?

The current discussion "When a <fig> is inserted, it should contain a <title> element" prompts me to ask what I'm sure is a trivial question. I am using Oxygen to edit XML in text mode. I would like an XML element <dateUpdated> to be updated automatically on save. I am aware of the of the ${date(pattern)} editor variable, but don't know how to trigger an action on the save event or indeed what type of code can be run once the event is detected. The online example <https://www.oxygenxml.com/doc/versions/20.0/ug-editorEclipse/topics/api_faq_auto_modify_content_save.html> seemed to be in a DITA context and require the Plugins SDK, neither of which I'm familiar with. With thanks, David Levy