it is present and zero. This is useful for users with terminals or fonts
that do not correctly support UTF-8 line drawing characters. GitHub
issue 927, reported by Hiroaki Yamazoe and Akinori Hattori.
terminals (I'm looking at you, putty) which disable the vt100 ACS mode
switching sequences in UTF-8 mode.
Also on terminals without ACS at all, use ASCII equivalents where
obvious.