ray of all missing values of
the given size. If no input <var class="var">sz</var> is given, the result is a scalar missing
string.
</p>
<p><code class="code">NaS</code> is the <code class="code">string</code> equivalent of <code class="code">NaN</code> or <code class="code">NaT</code>. It
represents a missing, invalid, or null value. <code class="code">NaS</code> values never compare
equal to any value, including other <code class="code">NaS</code>s.
</p>
<p><code class="code">NaS</code> is a convenience f