The fact that the field name is "BG_USER_##" indicates it is a custom field rather than a built in field. Somebody with adminstrative access to the project can look at the project Customization information and tell you what Type of field it is.
It is also possible that custom code has been added to the workflow to modify the way the data is displayed. That is also something that somebody with administrative access to the project could tell you.
It is also possible that custom code has been added to the workflow to modify the way the data is displayed. That is also something that somebody with administrative access to the project could tell you.
