inconsistent bindings of backspace and delete between X and xterm

[Dale Hagglund <rdh@yottayotta.com>]

[I read bug-gnu-emacs via the gatewayed newsgroup.  Please cc me on
any followups, if possible. --rdh]

I was experimenting with emacs 21.3 running under X and then inside
xterm, and I observe the following behaviour.  In all cases, I started
emacs with the -q flag.

1. Under X, the backspace and delete keys generate the respective
   window-system events, each of which is mapped to DEL via the
   function-key-map, which is then bound to
   `delete-previous-character'.

2. Under xterm version 4.2.99.903(174), backspace sends DEL and delete
   sends `ESC [ 3 ~'.  Emacs treats DEL, of course, as
   `delete-previous-character', but `ESC [ 3 ~' is mapped to the event
   <deletechar>, which is bound to `delete-char'.

This behaviour is inconsistent.  In each case, emacs can distinguish
between the Delete and Backspace keys, but in one environment they
behave, and in the other, differently.  Also, is there any reason why
`ESC [ 3 ~' shouldn't be mapped to <delete> instead of <deletechar>.

Is this intentional?  I don't really care which way the inconsistency
is resolved, but I think it should be.

Dale Hagglund.