каждый первый элемент в строках

<!-- Шаблон вывода информационного элемента -->
   <xsl:template match="informationsystem_item">

      <td class="news-all n{@id}">
               <xsl:if test="position() = 1">
            <xsl:attribute name="class">news-all second</xsl:attribute>
         </xsl:if>
         <table class="into">
            <tr>
               <td>
                  <!-- Изображение для информационного элемента (если есть) -->
                  <xsl:if test="image_small!=''">
                     <a href="{url}" class="news_title">
                        <img src="{dir}{image_small}" class="news_img" alt="" align="left"/>
                     </a>
                  </xsl:if>
               </td>
               <td>
                  <a href="{url}" hostcms:id="{@id}" hostcms:field="name" hostcms:entity="informationsystem_item">
                     <xsl:value-of disable-output-escaping="yes" select="name"/>
                  </a>
                  <xsl:if test="description != ''">
                     <div hostcms:id="{@id}" hostcms:field="description" hostcms:entity="informationsystem_item" hostcms:type="wysiwyg"><xsl:value-of disable-output-escaping="yes" select="substring(description, 0, 50)"/></div>
                  </xsl:if>
                  <div class="otstup"></div>
                  <a class="news-readmore" href="{url}" hostcms:id="{@id}" hostcms:field="name" hostcms:entity="informationsystem_item">
                     читать <img src="/skin/img/arrow-news.jpg" width="10px" alt=""/>
                  </a>
               </td>
            </tr>
         </table>
         
      </td>
      
      <!--защита на случай, если число новостей на странице не кратно 3-->
      <xsl:if test="position() = last() and position() mod 3 &gt; 0">
         <xsl:if test="1 - (position() mod 3) &gt; -2">
            <xsl:text disable-output-escaping="yes">
               &lt;td&gt;&#160;&lt;/td&gt;
            </xsl:text>
            <xsl:if test="1 - (position() mod 3) &gt; -1">
               <xsl:text disable-output-escaping="yes">
                  &lt;td&gt;&#160;&lt;/td&gt;
               </xsl:text>
            </xsl:if>
         </xsl:if>
      </xsl:if>
      
      <!--Для формирования по 3 новости в строку-->
      <xsl:if test="position() mod 3 = 0 and position() != last()">
         <xsl:text disable-output-escaping="yes">
            &lt;/tr&gt;&lt;tr&gt;
         </xsl:text>
      </xsl:if>
      
   </xsl:template>

<xsl:if test="(position() - 1) mod 3 = 0">
   <xsl:attribute name="class">news-all second</xsl:attribute>
</xsl:if>