They are fields that cannot be removed in the Modify table view dialog.
- Fields on the current layout are marked with a lock icon in the Modify Table View dialog box, indicating they can’t be removed from the list. You can prevent these fields from displaying in Table View by clearing their checkbox. "
All the fields that can't be removed are on the Body part of the current layout. 2 fields are not marked with a lock icon, both are on the Header part of the current layout. Is this the reason why they can be removed ?
Because they are in the header not the body. Assume that header fields are there for layout purposes whereas body fields are there for data purposes and perhaps logic and as thus, should not be removed via the table view dialog.
Good enough reason. Thank you.