Shortbow and longbow names aren't consistent on the THAC0 part of the inventory screen.
If a longbow is equipped... Longbow: -1
If a shortbow is equipped... Arrow to Hit: -2
I only tested this inconsistency after I noticed "Arrow to Hit". Just what is "arrow to hit"? o_o It doesn't matter if Imoen or Khalid is holding the shortbow: it's the same "arrow to hit" deal. I did not test other types of arrows. That may make a difference. n.n