 the text do not require
<kbd>.REF</kbd> (see
<a href="#parenthetical">Inserting parenthetical references into the text</a>.)
</p>

<p>
Before you use REF, you must create a <kbd>refer</kbd> block
containing <kbd>refer</kbd> commands (see
<a href="#rcommands-ref">Required refer commands</a>
in the tutorial, above).
</p>

<p>
REF usage always looks like this:
<br/>
<span class="pre-in-pp">
  .REF
  .[
  keyword(s)
  .]
  .REF
</span>
Notice that REF &#8220;brackets&#8221; the <kbd>refer</kbd> instructions,
a