ZOA differentiates between mandatory and optional data fields / questions. Required data fields are marked with a small circle to the left of the data field name. In the example below, the data fields "Gap assessment started", "Gap assessment finished" and "Contact details" are mandatory while "Approval status" is an optional data field.  

Only mandatory data fields / questions are taken into consideration for the statistics such as the percentage of completion. In the example above, there are 99 mandatory data fields and 62 still missing.