title: Formatter VS DateFormat inconsistencies
body: <p><strong>Premise</strong></p>
  
  <p>This question might be reasonably deemed as too broad or opinion-driven, but I feel I've got to risk it anyway.</p>
  
  <p><strong>Problem</strong></p>
  
  <p>There is a number of incomprehensible inconsistencies between the date/time conversion formats illustrated in Java's <a href="https://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html#dt" rel="nofollow noreferrer">Formatter</a> VS <a href="http://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html" rel="nofollow noreferrer">SimpleDateFormat</a> APIs. </p>
  
  <p>For instance:</p>
  
  <ul>
  <li><code>M</code> represents the minute in <code>Formatter</code> but the month in <code>SimpleDateFormat</code> <strong>and vice-versa</strong></li>
  <li><code>S</code> and <code>L</code> respectively represent second and millisecond in <code>Formatter</code>, but <code>s</code> and <code>S</code> respectively represent second and millisecond in <code>SimpleDateFormat</code></li>
  <li><code>A</code> and <code>a</code> respectively represent the long/short name of the day in week in <code>Formatter</code> but the same output in <code>SimpleDateFormat</code> is represented by <code>&lt;= 2</code> vs <code>&gt; 2</code> consecutive occurrences of <code>E</code>, while <code>a</code> represents the AM/PM marker instead, in <code>SimpleDateFormat</code></li>
  <li>Etc.</li>
  </ul>
  
  <p><strong>Question</strong>(s)</p>
  
  <ul>
  <li>Is there some rationalization justifying these inconsistences, e.g. maybe the two classes use different standards? </li>
  <li>I can only infer from <code>Formatter</code>'s API that:
  
  <blockquote>
    <p>The types are similar to but not completely identical to those defined by GNU date and POSIX <code>strftime(3c)</code>.</p>
  </blockquote></li>
  <li><code>SimpleDateFormat</code> does not seem to bother even mentioning the rationale for its conventions</li>
  <li>Are these two conventions arbitrary <strong>and</strong> inconsistent by design, or are there implicit standards that I am not aware of, that justify these inconsistences?</li>
  </ul>