The field that you choose under Field for publishing is a kind of second owner field with which a document can be allocated to a second owner (user or group user). For many archives this function is irrelevant, however, it can be a very important function indeed. Look at the following instance:
A knowledge archive is continually fed with new documents by several project managers. Each project manager is responsible for the documents she adds. At the same time she can make the documents available to an extended circle of users.
After this option has been activated, the input mask will show a second combo box with document owners. This way each primary owner of a document can set a second, subordinate owner. It goes without saying that the main user settings apply also in the extended owner environment.
The field that you specify here must be of the type 'Definition'. See 12.3.3.