Setting a "time" type variable to "missing/not available"

1. What is the issue? Please be detailed.
I am designing a form that includes collecting fields on date and time of admission (to a hospital). The data will be collected from medical records, and I am interested in documenting clearly when the fields of date and time are "missing" or "not available" in the medical records. I would like to have the fields as "required" but still be able to indicate if the data are "not available".
I am not aware if this feature is available?

2. What steps can we take to reproduce this issue?

3. What have you tried to fix the issue?

4. Upload any forms or screenshots you can share publicly below.

Some options to consider...

  • Use a select_one asking if the date is available before asking for the date. You can put both questions in a group with a field-list and make the date question relevant only if the answer to the select_one is yes.
  • Use a required select_one after the unrequired date question asking them to confirm that the data is missing if they leave the date blank.
  • Put a hint asking them to enter a likely invalid date (Jan 1, 1970) if the data is missing.

Personally, I like the first option.