><td> OnHeader   </td></tr>
</table>
<br>
<ul>
<li>The <b>filename</b> represents a disk file that will be used for input or output.<br>
<li>The <b>stream</b> represents user data that will be passed to the callback.<br>
<li>The <b>callback</b> represents a <i>c-style</i> function that is called by the library when it needs to read or write transferred data.<br>
&nbsp; ( Callbacks should always be declared using the <tt>cdecl</tt> directive. )
<li>The <b>event</b> represents a component-style procedure that