On Saturday 12 May 2007, Bart Schaefer wrote:
> On May 12,  2:32pm, Andrey Borzenkov wrote:
> }
> } Arguably zsh should treat \M-x and ESC-x interchangeably; I believe it
> } even was the case once but my memory fails me here.
>
> It's never interchanged them, but the "bindkey -m" command initializes
> all the \M- sequences to be the same as the ESC- sequences.  Nowadays
> that also turns off multibyte support, so it's not as desirable.
>

zsh also adds those ESC mappings to default emacs keymap automatically BTW.