normal-erase-is-backspace

normal-erase-is-backspace is a variable defined in `simple.el'.
Its value is

maybe

Documentation:
Set the default behavior of the Delete and Backspace keys.

If set to t, Delete key deletes forward and Backspace key deletes
backward.

If set to nil, both Delete and Backspace keys delete backward.

If set to 'maybe (which is the default), Emacs automatically
selects a behavior. On window systems, the behavior depends on
the keyboard used. If the keyboard has both a Backspace key and
a Delete key, and both are mapped to their usual meanings, the
option's default value is set to t, so that Backspace can be used
to delete backward, and Delete can be used to delete forward.

If not running under a window system, customizing this option
accomplishes a similar effect by mapping C-h, which is usually
generated by the Backspace key, to DEL, and by mapping DEL to C-d
via `keyboard-translate'. The former functionality of C-h is
available on the F1 key. You should probably not use this
setting if you don't have both Backspace, Delete and F1 keys.

Setting this variable with setq doesn't take effect. Programmatically,
call `normal-erase-is-backspace-mode' (which see) instead.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 21.1 of Emacs.