↑ "Backwards" means to the left for left-to-right languages.
↑ Many typewriters don't advance accent characters, so that no backspace is needed. However, it is still used e.g. for combining "o" with "/".
↑ There is no reason why a digital display or typesetting system could not be designed to allow backspace composition, a.k.a. overstrike, if an engineer chose to do that. As most contemporary computer display and typesetting systems are raster graphics-based rather than character-based (as of the year 2012), they make overstrike actually quite easy to implement. However, the use of proportional-width rather than fixed-width (monospaced) fonts makes the practical implementation of overstrike more complicated, and the original physical motivation for the technique is not present in digital computer systems.
