title: How to Interpret NLTK Brill Tagger Rules
body: <p>For the generated Brill Tagger Rule:</p>
  
  <pre><code>Rule('016', 'CS', 'QL', [(Word([1, 2, 3]),'as')])
  </code></pre>
  
  <p>I know:
  <code>'CS'</code> is subordinating conjunction
  <code>'QL'</code> is qualifier</p>
  
  <p>I guess:
  <code>[(Word([1, 2, 3]),'as')]</code> means the condition of the rule. It stands for the word <code>'as'</code> appear as the first, second or third position before the target word. Target word is word that is going to be tagged by POS tag.</p>
  
  <p>I do not know:
  What is the meaning for <code>'016'</code>?
  How to interpret the rule as a whole?</p>