You can find the identification fields directly from the builder welcome page. This identification will be necessary to assign a field to a patient ID, a record date (or inclusion date) and a potential date of first visit when the study protocol contains follow-up visits
When you want to assign a field or update the field assign to the patient ID, record date or first visit you first need to click on update, choose the field you want to assign in the proposed list and click on submit.
You can see below an exemple of the proposal list of CRF field you can assign to a subject ID
