title: C++ comment style: /*M ... M*/, what 'M' stands for?
body: <p>I have seen some 3rd party source code with comments in <code>/*M  ...  M*/</code> style.  But what 'M' stands for?   (Perhaps it is used with some kind of version control, or code documentation system (like doxygen)?)</p>
  
  <p>I saw it in many (if not all) source code files in opencv.</p>
  
  <p>You may browse Itseez's opencv repository under GitHub by clicking
  <a href="https://github.com/Itseez/opencv" rel="noreferrer">here</a>.</p>
  
  <p>Oh. I forget to mention, the comment style seems to exist only in the head of the file, and it seems to declare the license.</p>
  
  <p><a href="https://github.com/Itseez/opencv/blob/master/include/opencv2/opencv.hpp" rel="noreferrer">Example</a>:</p>
  
  <blockquote>
  <pre><code>/*M///////////////////////////////////////////////////////////////////////////////////////
  //
  //  IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
  //
  //  By downloading, copying, installing or using the software you agree to this license.
  //  If you do not agree to this license, do not download, install,
  //  copy or use the software.
  //
  //
  //                           License Agreement
  //                For Open Source Computer Vision Library
  
  [...]
  //
  //M*/
  </code></pre>
  </blockquote>