title: What is a POSIX function according to Microsoft
body: <p>I'm reading old C code for dos (1992), in that code, I found a call to <code>filelength</code>.</p>
  
  <p>I went to <a href="https://msdn.microsoft.com/library/ms235394%28v=vs.80%29.aspx" rel="nofollow noreferrer">MSDN</a> to learn about this function:</p>
  
  <blockquote>
    <p>This POSIX function is deprecated beginning in Visual C++ 2005. Use the ISO C++ conformant <code>_filelength</code> instead.</p>
  </blockquote>
  
  <p>I try to find more about this function in POSIX documentation, but I found nothing but MSDN reference.</p>
  
  <p>So:</p>
  
  <ul>
  <li>What does mean "POSIX" in this context? </li>
  <li>Does this function exists out of Microsoft libraries?</li>
  </ul>