[milkfish]

There is some ambiguity when trying to use the code with taps instead of tones. For instance, "A" is a short followed by a long, while "I" is two shorts. If all I hear is two closely spaced taps, I cannot tell which one was intended. If some other character follows, however, this helps break the ambiguity because one can hear whether there is a long or a short gap after the second tap.

With tones there isn't this problem, because the trailing edge of the tone carries information.