title: Use doxygen to document members of a c structure outside of the structure definition
body: <p>I am using doxygen to comment my C code. I am making use of a foreign API (i.e. not my own) for which documentation is scarce so I intend to document some of that API within my own source files. I <em>do</em> have the header file for the foreign API but it is not practical to add my own comments to that file.</p>
  
  <p><strong>Foreign Header</strong></p>
  
  <pre><code>struct foreignstruct
  {
      int a;
      int b;
  };
  </code></pre>
  
  <p><strong>My Header</strong></p>
  
  <pre><code>/** My structure comments... */
  struct mystruct
  {
      /** Describe field here... */
      int field;
  };
  
  /** @struct foreignstruct
   *  @brief This structure blah blah blah...
   *  @??? a Member 'a' contains...
   *  @??? b Member 'b' contains...
   */
  </code></pre>
  
  <p>What tag do I use in place of <code>@???</code> to get the correct doxygen output (where 'correct' means generated output for <code>mystruct</code> and <code>foreignstruct</code> are the same)?</p>