title: autoindent is subset of smartindent in vim?
body: <blockquote>
    <p><strong>:help autoindent</strong> : Copy indent from current line when starting a new line (typing 
    in Insert mode or when using the "o" or "O" command). ...</p>
    
    <p><strong>:help smartindent</strong> : Do smart autoindenting when starting a new line.  Works for C-like
     programs, but can also be used for other languages. ...</p>
    
    <p><strong>Normally 'autoindent' should also be on when using 'smartindent'.</strong>
    An indent is automatically inserted:</p>
    
    <ul>
    <li>After a line ending in '{'.</li>
    <li>After a line starting with a keyword from 'cinwords'.</li>
    <li><p>Before a line starting with '}' (only with the "O" command).</p>
    
    <p>When typing '}' as the first character in a new line, that line is
       given the same indent as the matching '{'. ...</p></li>
    </ul>
  </blockquote>
  
  <p><strong>smartindent</strong> also coping indent from current line when starting a new line. That means <strong>autoindent</strong> feature is subset of <strong>smartindent</strong> feature and no need of <strong>autoindent</strong> if <strong>smartindent</strong> is on, right? Why <strong>autoindent</strong> should be turn on?</p>