title: Cascading RegexSplitGenerator confused
body: <p>I am looking the Cascading tutorial on its official website. It has the following input:</p>
  
  <pre><code>doc_id  text
  doc01   A rain shadow is a dry area on the lee back side of a mountainous area.
  doc02   This sinking, dry air produces a rain shadow, or area in the lee of a mountain with less rain and cloudcover.
  doc03   A rain shadow is an area of dry land that lies on the leeward (or downwind) side of a mountain.
  doc04   This is known as the rain shadow effect and is the primary cause of leeward deserts of mountain ranges, such as California's Death Valley.
  doc05   Two Women. Secrets. A Broken Land. [DVD Australia]
  </code></pre>
  
  <p>It looks like the TSV format.</p>
  
  <p>And in its WordCount program, it has the following code:</p>
  
  <pre><code>Fields token = new Fields("token");
  Fields text = new Fields("text");
  RegexSplitGenerator splitter = new RegexSplitGenerator(token, "[ \\[\\]\\(\\),.]");
  </code></pre>
  
  <p>So I am just confused what  "[ \[\]\(\),.]" means? Is it just grep the second part of the input file each line and named in as "token" Field?</p>