I am struggling with taking a collection of <day> elements and formatting them in groups of 5, to simulate a weekday calendar in PDF output. I've looked through the archives and not been able to find anything that gets me further than where I am stuck.

<xsl:template match="course">
<xsl:variable name="v_dayCount">
<xsl:value-of select="count(descendant::day)"/>
</xsl:variable>
<fo:block margin-top="12pt">
<fo:block text-align="center" id="@id">
<fo:table border="1pt solid black">
<fo:table-column column-width="100pt"/>
<fo:table-body>
<xsl:for-each-group select="descendant::day" group-ending-with="day[(count(preceding::day[ancestor::course[1]])+1) mod 5 = 0]">

<xsl:sort select="position()" order="ascending" data-type="number"/>

<fo:table-row height="15pt" background-color="gray" border-top="1pt solid black">
<xsl:for-each select="current-group()">
<xsl:apply-templates select="self::day" mode="calendartitle"/>
</xsl:for-each>

It seems the for-each and apply-templates can be combined to
  <xsl:apply-templates select="current-group()" mode="calendartitle"/>