$category_id = null;

if ( $option == "com_content" ) {

  if ( $view == "category" ) {

   /* category list pages (blog or list style) */

   $category_id = (int)$id;

  } else if (array_key_exists("catid",$_REQUEST)) {

   /* if the category id is in the URL */

   $category_id = (int)JRequest::getInt("catid",0);

  }

  if ( $category_id === null && $view == "article" ) {

   /* if it's an article page without the catid mentioned in the url */

   $nullDate = $db->Quote( $db->getNullDate() );

   $my_id = $db->Quote( $db->getEscaped( (int)$id ) );

   $jnow  =& JFactory::getDate();

   $now    = $db->Quote( $db->getEscaped( $jnow->toMySQL() ) );

   $query = "SELECT  title,  id,  catid "

       . " FROM #__content WHERE id = $my_id AND state = 1"

       . " AND ( publish_up = $nullDate "

       . " OR publish_up <= $now )"

       . " AND ( publish_down = $nullDate "

       . " OR publish_down >= $now  )";

   $db->setQuery( $query, 0, 1 );

   $row = $db->loadObject();

   $category_id = $row->catid;

  }

}

/* Now customise any of the following rules for your use.

 * $category_id will correspond to the category id of the

 * article being displayed (if one is being displayed!)

 */

if (($category_id == 41) & MM_LOGGED_IN ) return 80;

if (($category_id == 42) & MM_LOGGED_IN ) return 80;

if (($category_id == 43) & MM_LOGGED_IN ) return 80;

if (($category_id == 44) & MM_LOGGED_IN ) return 80;

if (($category_id == 45) & MM_LOGGED_IN ) return 80;

if (($category_id == 41) & MM_NOT_LOGGED_IN ) return 76;

if (($category_id == 42) & MM_NOT_LOGGED_IN ) return 76;

if (($category_id == 43) & MM_NOT_LOGGED_IN ) return 76;

if (($category_id == 44) & MM_NOT_LOGGED_IN ) return 76;

if (($category_id == 45) & MM_NOT_LOGGED_IN ) return 76;

else return 36;