title: Significance of question mark in Java cron
body: <p>Source Wikipedia:   </p>
  
  <blockquote>
    <p><strong>Question mark</strong> (?) is used instead of '*' for leaving either day-of-month or day-of-week blank.</p>
  </blockquote>
  
  <p>The above statement is not making much sense to me.</p>
  
  <p>So if I write some cron as <strong><code>0 0 0 ? * *</code></strong> then does it mean first of every month or it means it will execute daily?</p>
  
  <p>It is a bit confusing as Java crons start with seconds while other crons start with minute.</p>