title: How to format BC dates (like "-700-01-01")?
body: <p>How to format ISO dates BC with Moment.js?</p>
  
  <pre><code>moment("-700-01-01").year();     // 700 (WRONG)
  moment("-0700-01-01").year();    // 700 (WRONG)
  moment("-000700-01-01").year();  // -700 (RIGHT)
  </code></pre>
  
  <p>For some reason a year notation with 6 digits works. Is that the "right" way? Why doesn't notation like <code>"-700-01-01"</code> work?</p>