You can think of the “upfront” fields as mandatory fields. Both input and dropdown fields can have the upfront requirement. All the fields marked as required upfront represent the data we need to collect from the customers before they can preview their book. On the book for couples called “Better together”, the creators are asking people to select their gender, type in their name and partner’s name and choose whether they are straight or gay. All this data is required upfront, because the cover, the content and the avatars presented to be customized are all different based on these values.
An example of a field that’s not required upfront is a “Dedication” as it can always be added after the initial preview has been generated.