What feature is at play when Ctrl+Shift+Alt+U,E "types" an unprintable hex 000E?
Ctrl-Shift-U is the short-cut to start entering a full unicode character by hand. For example, here I've typed: Ctrl-Shift-U 0 0 b 0 enter to get the degree symbol: ° which is unicode 00b0. Here is 2665, the heart: ♥
For a list of unicode symbols start here: http://en.wikipedia.org/wiki/Unicode