mac-auto-ascii-mode is an interactive compiled Lisp function in
‘term/mac-win.el’.
(mac-auto-ascii-mode &optional ARG)
Toggle Mac Auto ASCII mode.
With a prefix argument ARG, enable Mac Auto ASCII mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
the mode if ARG is omitted or nil.
Mac Auto ASCII mode automatically selects the most-recently-usedASCII-capable keyboard input source on some occasions: afterprefix key (bound in the global keymap) press such as C-x andM-g, and at the start of minibuffer input.
Strictly speaking, its implementation has a timing issue: the
Lisp event queue may already have some input events that have
been processed by some previous keyboard input source but yet to
be processed by the Lisp interpreter.