
<a href="#matchtime">match-time capture</a> over the empty string.
</p></li>

</ul>


<h3><a name="op-behind"></a><code>lpeg.B(patt [, n])</code></h3>
<p>
Returns a pattern that
matches only if the input string matches <code>patt</code>
starting <code>n</code> positions behind the current position.
(The default value for <code>n</code> is 1.)
If the current position is less than or equal to <code>n</code>,
this pattern fails.
</p>

<p>
Like the <a href="#op-len">and predicate</a>,
this pattern never consum