3 class="subsection"> 63.1.4 Binary floating-point input and output </h3>

<p><code>numericalio</code> functions can read and write 8-byte IEEE 754 floating-point numbers.
These numbers can be stored either least significant byte first or most significant byte first,
according to the global flag set by <code>assume_external_byte_order</code>.
If not specified, <code>numericalio</code> assumes the external byte order is most-significant byte first.
</p>
<p>Other kinds of numbers are coerced to 8-byte floats;