Perl 6's approach to xor is consistent with the linguistic sense of
'xor' ("You may have a soup (x)or a salad (x)or a cocktail"), and also
with the IEEE 91 standard for logic gates. See:
http://ozark.hendrix.edu/~burch/logisim/docs/2.1.0/libs/gates/xor.html
for a concise explanation of both these senses of xor.
Damian
