by
      one <a href="#option_indentUnit"><code>indentUnit</code></a>.
      If shift was held while pressing tab, un-indent all selected
      lines one unit.</dd>
      <dt><code>"indent"</code></dt>
      <dd>Indent the line the 'correctly', based on its syntactic
      context. Only works if the
      mode <a href="#indent">supports</a> it.</dd>
      <dt><code>"default"</code></dt>
      <dd>Do not capture tab presses, let the browser apply its
      default behaviour (which usually means it skips to t