title: Restrictions on Canonical NaNs in IEEE 754-2008
body: <p>The usage of canonical NaN in the standard is confusing to me. For binary floats, it doesn't actually state what a canonical NaN is. For decimal floats it states (paeg 11): </p>
  
  <blockquote>
    <p>A NaN is in its preferred (canonical) representation if the bits G_6 through G_(w+4) are zeroand the encoding of the payload is canonical.</p>
  </blockquote>
  
  <p>The only restriction I can find on binary floats is that there should be a canonical version of any NaN. Therefore at least 1 NaN must exist per bit-width.</p>
  
  <p>Is there an upper bound on the number of canonical NaNs that can be allowed? Can every NaN be canonical?</p>