 subtype = float8,
    subtype_diff = float8mi
);

SELECT '[1.234, 5.678]'::floatrange;
</pre><p>

   Because <code class="type">float8</code> has no meaningful
   <span class="quote">“<span class="quote">step</span>”</span>, we do not define a canonicalization
   function in this example.
  </p><p>
   When you define your own range you automatically get a corresponding
   multirange type.
  </p><p>
   Defining your own range type also allows you to specify a different
   subtype B-tree operator class o