Hidden fields in a data model:

Hidden fields in a data model serve a specific purpose in enhancing the organization and usability of data without cluttering the user interface. They are designed to be utilized in back-end processes or to aid in the creation of other datasets, allowing for more complex queries without immediate visibility to the end user.

The first choice correctly states that hidden fields will not be displayed to a Pivot user, ensuring that the user experience remains focused on the more relevant, visible fields. However, these hidden fields can still play a crucial role in defining other datasets. This allows data modelers to create intricate relationships and aggregations without overwhelming users with every available data point.

The other options either involve displaying hidden fields in ways that contradict their purpose, such as being visible to Pivot users or in the dataset editor, or suggest that they are always accessible in search results, which conflicts with the hidden nature of these fields. Thus, the essence of hidden fields is to maintain a tidy user interface while still allowing for advanced data manipulation behind the scenes.