The x11term.c here has been patched to change how Emacs names
"special" keys. The old way was to hard-code various function keys
(with different values if you were on a Sun or on anything else); the
new way is to generate a sequence which includes the X11 key name,
plus a shift/control/meta indicator[*].

 The sequence generated is
	ESC [ <keysm> ~
eg
	ESC [ F 6 ~
for the F6 key.

 If the key doesn't have a keysym (for example, the Remove key on DEC
LK201 keyboards), the hexadecimal keysym for the key is generated, eg
	ESC [ 1 0 0 0 f f 0 0 ~
for the LK201 Remove key.

 Shift, control, and meta being down are indicated by a "s-", "c-", or
"m-" in front of the sequence generated, eg
	ESC [ c - F 6 ~
for C-F6.

 For backwards compatability, the cursor keys still generate C-f, C-b,
C-n, and C-p.

 The keysym names are the same names that xev will give you, which
means that you can use it to figure out what that oddball key is
called.

[*: Keysyms are generated for all keys that don't generate characters,
    have keysyms and aren't claimed to be modifier keys. This can
    unfortunately lead to problems, as sometimes NumLock is not
    considered a modifier key.]