Coldfusion MX7 is actually right! NaN is numeric in the same
sense that infinity is numeric. MX7 is also right in saying that
NaN, just like infinity, cannot be converted to a number. In fact,
it cannot even be converted to itself! One definition of NaN is:
x is NaN if and only if (x = x) is false.
However, this makes arithmetic assumptions that fail in the
real world of computers. CF8 gets it right. To avoid inconsistency
in coding, IsNumeric("NaN") should return False.