t1</code> or <code>patt2</code>
      (ordered choice)</td></tr>
<tr><td><a href="#op-sub"><code>patt1 - patt2</code></a></td>
  <td>Matches <code>patt1</code> if <code>patt2</code> does not match</td></tr>
<tr><td><a href="#op-unm"><code>-patt</code></a></td>
  <td>Equivalent to <code>("" - patt)</code></td></tr>
<tr><td><a href="#op-len"><code>#patt</code></a></td>
  <td>Matches <code>patt</code> but consumes no input</td></tr>
<tr><td><a href="#op-behind"><code>lpeg.B(patt, n)</code></a></td>
  <td>Match