Add users' Initials to the footer

I have an Excel document that I want to control the revision in the footer. In the footer I currently have Revised: &[Date] , lks The lks is the initials of the person who changed the document last. The problem with this is the person has to remember to go into the custom footer and add their initials.

Is there a command like &[Date] that pulls the person's username from Microsoft office automatically?

If not could a macro be created that would have a popup window that ask the person to enter their initials and then it would be entered into the footer? It would be really cool if it popped up when the person hit the save button but that might be harder.

Thanks

Perfect. I didn't know you could have a macro run automatically on save. Does that go into the macro itself or somewhere else.

Thank you