Solved it myself. Many online sources say that NC Form D-400 - Line 26EU will display the entry "E" if your answer to NC Form D-422 - Line 3 includes checking the box to indicate that you are a fisherman or farmer. Even if you leave this box unchecked, there is another item that can fill 26EU with an E. Here it is:
Right click on the E and then select DATA SOURCE. The modal that pops up explains that the Code "E" will calculate for 2 reasons:
-- The Farmer/Fisher election previously mentioned,
OR
-- IF any of the 4 values shown at Line 25 on Form D-422A is greater than ZERO.
