Unfortunaltely I still have a problem with xsl:for-each-group and my
xml example.
For a better understanding the test-xml-file:

<root>
    <element>
        <h1>h1</h1>
        <h2>h2_1</h2>
        <para>para_1</para>
        <para>para_2<emp>auszeichnung</emp></para>
        <para>para_3</para>
        <para>para_4</para>
        <para>para_5</para>
        <h2>h2_2</h2>
        <para>para_6</para>
        <h3>h3_1</h3>
        <para>para_7</para>
        <h5>h5_1</h5>
        <para>para_8</para>
        <para>para_9<emp>auszeichnung</emp></para>
        <para>para_10</para>
        <h4>h4_1</h4>
        <para>para_11</para>
        <para>para_12</para>
        <h2>h2_3</h2>
        <para>para_13</para>
        <para>para_14</para>
        <para>para_15</para>
        <h3>h3_2</h3>
        <para>para_16<emp>auszeichnung</emp></para>
        <para>para_17</para>
        <para>para_18</para>
        <h4>h4_2</h4>
        <para>para_19</para>
        <para>para_20</para>
        <h5>h5_2</h5>
        <para>para_21</para>
        <para>para_22<emp>auszeichnung</emp></para>
        <para>para_23</para>
    </element>
</root>

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="2.0">
    <xsl:output indent="yes"/>

    <xsl:template match="/">
        <set>
            <book>
                <bookinfo/>
                <xsl:apply-templates/>
            </book>
        </set>
    </xsl:template>

    <xsl:template match="element">
        <xsl:apply-templates select="h1|h2[1]"/>
    </xsl:template>

    <xsl:template match="h1">
        <title>
            <xsl:apply-templates/>
        </title>
    </xsl:template>

    <xsl:template match="h2">
        <xsl:for-each-group select=".|following-sibling::*"
group-starting-with="h2|h3|h4|h5">
            <xsl:choose>
                <xsl:when test="current-group()[self::h2]">
                    <chapter>
                        <title>
                            <xsl:apply-templates/>
                        </title>
                        <xsl:copy-of select="current-group()[self::para]"/>
                        <xsl:choose>
                            <xsl:when
test="current-group()[following-sibling::h3]">
                                <xsl:call-template name="h3"/>
                            </xsl:when>
                        </xsl:choose>
                    </chapter>
                </xsl:when>
            </xsl:choose>
        </xsl:for-each-group>
    </xsl:template>

    <xsl:template name="h3">
        <sect1>
            <title>
                <xsl:apply-templates/>
            </title>
            <xsl:copy-of select="current-group()[self::para]"/>
        </sect1>
    </xsl:template>
</xsl:stylesheet>

<set>
   <book>
      <bookinfo/>
      <title>h1</title>
      <chapter>
         <title>h2_1</title>
         <para>para_1</para>
         <para>para_2<emp>auszeichnung</emp>
         </para>
         <para>para_3</para>
         <para>para_4</para>
         <para>para_5</para>
         <sect1>
            <title>h2_1</title>
            <para>para_1</para>
            <para>para_2<emp>auszeichnung</emp>
            </para>
            <para>para_3</para>
            <para>para_4</para>
            <para>para_5</para>
         </sect1>
      </chapter>
      <chapter>
         <title>h2_2</title>
         <para>para_6</para>
         <sect1>
            <title>h2_2</title>
            <para>para_6</para>
         </sect1>
      </chapter>
      <chapter>
         <title>h2_3</title>
         <para>para_13</para>
         <para>para_14</para>
         <para>para_15</para>
         <sect1>
            <title>h2_3</title>
            <para>para_13</para>
            <para>para_14</para>
            <para>para_15</para>
         </sect1>
      </chapter>
   </book>
</set>

But instead of
...
<sect1>
<title>h2_1</title>
<para>para_1</para>
<para>para_2<emp>auszeichnung</emp></para>
<para>para_3</para>
<para>para_4</para>
<para>para_5</para>
</sect1>
...

...
<sect1>
<h3>h3_1</h3>
<para>para_7</para>
</sect1>
...

and so on. Unfortunately I cannot see the problem. IsnB4t it possible
to grab the content out of a xsl:for-each-group as I tried it using a
separate template?

I am really sorry for that perhaps basic question but I am dispaired
about that problem.