title: What is the format of this m4 file?
body: <p>I found <a href="https://github.com/dpisarenko/db-api/blob/songcontest1/now/schema.m4" rel="nofollow">this</a> m4 file in one of the open source projects.</p>
  
  <pre><code>changequote(«, »)dnl
  include(«../defs.m4»)dnl
  include(«tables.sql»)dnl
  include(«functions.sql»)dnl
  include(«triggers.sql»)dnl
  include(«api.sql»)dnl
  </code></pre>
  
  <p>What is m4?</p>
  
  <p>Is it the <a href="http://www.gnu.org/software/m4/m4.html" rel="nofollow">GNU M4</a> or something else?</p>