 charmap has a few visible fields used to describe it more
      precisely.  Mainly, one will look at <tt>charmap-&gt;platform_id</tt>
      and <tt>charmap-&gt;encoding_id</tt> that define a pair of values
      that can be used to describe the charmap in a rather generic way.</p>

      <p>Each value pair corresponds to a given encoding.  For example, the
      pair (3,1) corresponds to Unicode.  The list is defined in the
      TrueType specification but you can also use the file
      <tt>FT_TRUETYPE_ID