It doesn't matter; what matters is that both your (terminal-manipulating) program and terminal emulator agree on the symbols widths. Considering that they usual

It doesn't matter; what matters is that both your (terminal-manipulating) program and terminal emulator agree on the symbols widths. Considering that they usually won't (lots of terminal emulators have their own hand-crafted, statically linked wcwidth/wcswidth functions; the readline library also has them hard-coded, by the way), it's quite frustrating.