Отображение элементов в ИС (не более 20)

<?php

$oInformationsystem = Core_Entity::factory('Informationsystem', Core_Array::get(Core_Page::instance()->libParams, 'informationsystemId');

$Informationsystem_Controller_Show = new Informationsystem_Controller_Show($oInformationsystem);

$Informationsystem_Controller_Show
   ->limit($oInformationsystem->items_on_page)   
   ->parseUrl();

if (!is_null(Core_Array::getGet('vote'))
{
   $oSiteuser = Core_Entity::factory('Siteuser'->getCurrent();
   $entity_id = intval(Core_Array::getGet('id');

   if ($entity_id && !is_null($oSiteuser))
   {
      $entity_type = strval(Core_Array::getGet('entity_type');
      $vote = intval(Core_Array::getGet('vote');

      $oObject = Vote_Controller::instance()->getVotedObject($entity_type, $entity_id);

      if (!is_null($oObject))
      {
         $oVote = $oObject->Votes->getBySiteuser_Id($oSiteuser->id);

         $vote_value = $vote ? 1 : -1;

         $deleteVote = 0;
         // Пользователь не голосовал ранее
         if (is_null($oVote))
         {
            $oVote = Core_Entity::factory('Vote';
            $oVote->siteuser_id = $oSiteuser->id;
            $oVote->value = $vote_value;

            $oObject->add($oVote);
         }
         // Пользователь голосовал ранее, но поставил противоположную оценку
         elseif ($oVote->value != $vote_value)
         {
            $oVote->value = $vote_value;
            $oVote->save();
         }
         // Пользователь голосовал ранее и поставил такую же оценку как и ранее, обнуляем его голосование, как будто он вообще не голосовал
         else
         {
            $deleteVote = 1;
            $oVote->delete();
         }
         
         Core_Entity::factory('Informationsystem_Item', $entity_id)->clearCache();

         $aVotingStatistic = Vote_Controller::instance()->getRate($entity_type, $entity_id);

         Core_Page::instance()->response
         ->body(
            json_encode(array('value' => $oVote->value, 'item' => $oObject->id, 'entity_type' => $entity_type,
               'likes' => $aVotingStatistic['likes'], 'dislikes' => $aVotingStatistic['dislikes'],
               'rate' => $aVotingStatistic['rate'], 'delete_vote' => $deleteVote)
            )
         );
      }
   }

   Core_Page::instance()->response
         ->status(200)
         ->header('Pragma', "no-cache"
         ->header('Cache-Control', "private, no-cache"
         ->header('Vary', "Accept"
         ->header('Last-Modified', gmdate('D, d M Y H:i:s', time()) . ' GMT'
         ->header('X-Powered-By', 'HostCMS'
         ->header('Content-Disposition', 'inline; filename="files.json"';

   if (strpos(Core_Array::get($_SERVER, 'HTTP_ACCEPT', '', 'application/json' !== FALSE)
   {
      Core_Page::instance()->response->header('Content-type', 'application/json; charset=utf-8';
   }
   else
   {
      Core_Page::instance()->response
         ->header('X-Content-Type-Options', 'nosniff'
         ->header('Content-type', 'text/plain; charset=utf-8';
   }

   if(Core_Array::getRequest('_')
   {
      Core_Page::instance()->response
         ->sendHeaders()
         ->showBody();
      exit();
   }
}

Core_Page::instance()->object = $Informationsystem_Controller_Show;

<?php

$Informationsystem_Controller_Show = Core_Page::instance()->object;

$xslName = $Informationsystem_Controller_Show->item
   ? Core_Array::get(Core_Page::instance()->libParams, 'informationsystemItemXsl'
   : Core_Array::get(Core_Page::instance()->libParams, 'informationsystemXsl';

$Informationsystem_Controller_Show->addEntity(
   Core::factory('Core_Xml_Entity'
      ->name('ОтображатьСсылкуНаАрхив'->value(0)
)->addEntity(
   Core::factory('Core_Xml_Entity'
      ->name('ОтображатьСсылкиНаСледующиеСтраницы'->value(1)
)->addEntity(
   Core::factory('Core_Xml_Entity'
      ->name('ТекущаяГруппа'->value($Informationsystem_Controller_Show->group)
)->addEntity(
   Core::factory('Core_Xml_Entity'
      ->name('show_comments'->value(
         intval(Core_Array::get(Core_Page::instance()->libParams, 'showComments', 1))
      )
)->addEntity(
   Core::factory('Core_Xml_Entity'
      ->name('show_add_comments'->value(
         intval(Core_Array::get(Core_Page::instance()->libParams, 'showAddComment', 2))
      )
);

$Informationsystem_Controller_Show
   ->tags(TRUE)
   ->comments(TRUE);

if ($Informationsystem_Controller_Show->item == 0)
{
   $Informationsystem_Controller_Show->itemsForbiddenTags(array('text');
}
else
{
   if (Core_Array::getPost('add_comment' && Core_Array::get(Core_Page::instance()->libParams, 'showAddComment' != 0)
   {
      $Informationsystem_Controller_Show->cache(FALSE);

      $oLastComment = Core_Entity::factory('Comment'->getLastCommentByIp(
         Core_Array::get($_SERVER, 'REMOTE_ADDR'
      );

      $oXmlCommentTag = Core::factory('Core_Xml_Entity'
         ->name('document';

      $siteuser_id = 0;
      if (Core::moduleIsActive('siteuser')
      {
         $oSiteuser = Core_Entity::factory('Siteuser'->getCurrent();

         if ($oSiteuser)
         {
            $siteuser_id = $oSiteuser->id;
         }
      }

      $oComment = Core_Entity::factory('Comment';

      $allowable_tags = '<b><strong><i><em><br><p><u><strike><ul><ol><li>';
      $oComment->parent_id = intval(Core_Array::getPost('parent_id', 0));
      $oComment->active = Core_Array::get(Core_Page::instance()->libParams, 'addedCommentActive', 1) == 1 ? 1 : 0;
      $oComment->author = Core_Str::stripTags(Core_Array::getPost('author');
      $oComment->email = Core_Str::stripTags(Core_Array::getPost('email');
      $oComment->phone = Core_Str::stripTags(Core_Array::getPost('phone');
      $oComment->grade = intval(Core_Array::getPost('grade', 0));
      $oComment->subject = Core_Str::stripTags(Core_Array::getPost('subject');
      $oComment->text = nl2br(Core_Str::stripTags(Core_Array::getPost('text', $allowable_tags));
      $oComment->siteuser_id = $siteuser_id;

      $oInformationsystem_Item = Core_Entity::factory('Informationsystem_Item', $Informationsystem_Controller_Show->item);

      $oXmlCommentTag
         ->addEntity($oComment)
         ->addEntity($oInformationsystem_Item);

      if (is_null($oLastComment) || time() > Core_Date::sql2timestamp($oLastComment->datetime) + ADD_COMMENT_DELAY)
      {
         $oInformationsystem = $Informationsystem_Controller_Show->getEntity();

         if ($oInformationsystem->use_captcha == 0 || $siteuser_id > 0 || Core_Captcha::valid(Core_Array::getPost('captcha_id', Core_Array::getPost('captcha'))
         {
            // Antispam
            if (Core::moduleIsActive('antispam')
            {
               $Antispam_Controller = new Antispam_Controller();
               $bAntispamAnswer = $Antispam_Controller
                  ->addText($oComment->author, 'author'
                  ->addText($oComment->email, 'email'
                  ->addText($oComment->phone, 'phone'
                  ->addText($oComment->subject, 'subject'
                  ->addText($oComment->text, 'text'
                  ->execute();

               // Check e-mail
               if ($bAntispamAnswer)
               {
                  $bAntispamAnswer = Antispam_Domain_Controller::checkEmail($oComment->email);
               }
            }
            else
            {
               $bAntispamAnswer = TRUE;
            }

            if ($bAntispamAnswer)
            {
               $oComment->save();

               $oComment
                  ->dateFormat($oInformationsystem->format_date)
                  ->dateTimeFormat($oInformationsystem->format_datetime);

               $oInformationsystem_Item->add($oComment)->clearCache();

               $oXmlCommentTag->addEntity($oInformationsystem);

               // Отправка письма администратору
               $sText = Xsl_Processor::instance()
                  ->xml($oXmlCommentTag->getXml())
                  ->xsl(Core_Entity::factory('Xsl'->getByName(Core_Array::get(Core_Page::instance()->libParams, 'addCommentAdminMailXsl'))
                  ->process();

               $aFrom = array_map('trim', explode(',', EMAIL_TO));

               $oCore_Mail_Driver = Core_Mail::instance()
                  ->to(EMAIL_TO)
                  ->from($aFrom[0])
                  ->header('Reply-To', Core_Valid::email($oComment->email)
                     ? $oComment->email
                     : $aFrom[0])
                  ->subject(Core::_('Informationsystem.comment_mail_subject')
                  ->message(trim($sText))
                  ->contentType(Core_Array::get(Core_Page::instance()->libParams, 'commentMailNoticeType', 0) == 0
                     ? 'text/plain'
                     : 'text/html'
                  )
                  ->send();
            }
            else
            {
               $oXmlCommentTag->addEntity(Core::factory('Core_Xml_Entity'
                  ->name('error_antispam'->value(1)
               );

               $oComment->text = Core_Str::br2nl($oComment->text);
               $Informationsystem_Controller_Show->addEntity($oComment);
            }
         }
         else
         {
            $oXmlCommentTag->addEntity(Core::factory('Core_Xml_Entity'
               ->name('error_captcha'->value(1)
            );

            $oComment->text = Core_Str::br2nl($oComment->text);
            $Informationsystem_Controller_Show->addEntity($oComment);
         }
      }
      else
      {
         $oXmlCommentTag->addEntity(Core::factory('Core_Xml_Entity'
            ->name('error_time'->value(1)
         );

         $oComment->text = Core_Str::br2nl($oComment->text);
         $Informationsystem_Controller_Show->addEntity($oComment);
      }

      // Результат добавления комментария
      $xsl_result = Xsl_Processor::instance()
         ->xml($oXmlCommentTag->getXml())
         ->xsl(Core_Entity::factory('Xsl'->getByName(
            Core_Array::get(Core_Page::instance()->libParams, 'addCommentNoticeXsl')
         )
         ->process();

      $Informationsystem_Controller_Show->addEntity(
         Core::factory('Core_Xml_Entity'
            ->name('message'->value($xsl_result)
      );
   }
}

// В корне выводим из всех групп
if ($Informationsystem_Controller_Show->group == 0)
{
   /*$Informationsystem_Controller_Show->group(FALSE);*/
}

$Informationsystem_Controller_Show
   ->xsl(
      Core_Entity::factory('Xsl'->getByName($xslName)
   )
   ->itemsProperties(TRUE)
   ///->commentsProperties(TRUE)
   ->show();

Распечатайте $oInformationsystem->items_on_page в коде ТДС до ->show(), вероятно там будет иное значение.

что имеется ввиду?

var_dump$Informationsystem_Controller_Show
($oInformationsystem->items_on_page);
   ->limit($oInformationsystem->items_on_page)
   ->parseUrl();