Check if form is being newly submitted, or being edited


When the owner of a form is viewing submitted data, there is an option for them to edit a submitted form. I have a group of questions that I would like be hidden from the surveytakers who originally fill out the form, but which would appear for anyone who is editing an already previously submitted form,

One way that I’ve tried to do this is by using validation criteria that tests if form metadata has been initialized (such as ${_submission_time} = null), but I keep getting errors saying that the variable doesn’t exist.

Can anyone think of a creative solution to this problem?
Thank you,