ong
  double</code>), detects invalid numbers and throws exception each times an
  empty interval is created. This is a brief description and you should refer
  to the corresponding sections for a more precise description of the default
  policies. Unless you need some special behavior, this default type is
  usable in a lot of situations.</p>

  <p>After having completely defined the interval type (and its policies),
  the only thing left to do is to verify that the constants are defined and
  <code>std::n