emphasis role and $depth mod 2 = 1

["Julie May" <jmay@castlerockresearch.com>]

Hello every one,

Version: docbook-xsl-1.72.0

I hate to customize Docbook code without understanding what possible errors
code was designed to handle so I am going to ask before removing the test.

In the template <xsl:template match="emphasis">  I am trying to find out why
the test <xsl:when test="$depth mod 2 = 1"> exists and what it was designed
for.  Does anyone know?  (This same test is used for quote and may be used
elsewhere.)

I attempted to trigger the test but failed (by adding 2 then 3 periods to
the XML text, since this seems to be testing for an odd number of periods).

Thanks,

Julie May

Templates in question:
<!--lib/lib.xsl-->
<xsl:template name="dot.count">
  <!-- Returns the number of "." characters in a string -->
  <xsl:param name="string"/>
  <xsl:param name="count" select="0"/>
  <xsl:choose>
    <xsl:when test="contains($string, '.')">
      <xsl:call-template name="dot.count">
        <xsl:with-param name="string" select="substring-after($string,
'.')"/>
        <xsl:with-param name="count" select="$count+1"/>
      </xsl:call-template>
    </xsl:when>
    <xsl:otherwise>
      <xsl:value-of select="$count"/>
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>

<!--fo/inline.xsl, also exists in html -->
<xsl:template match="emphasis">
  <xsl:variable name="depth">
    <xsl:call-template name="dot.count">
      <xsl:with-param name="string">
        <xsl:number level="multiple"/>
      </xsl:with-param>
    </xsl:call-template>
  </xsl:variable>

  <xsl:choose>
    <xsl:when test="@role='bold' or @role='strong'">
      <xsl:call-template name="inline.boldseq"/>
    </xsl:when>
    <xsl:when test="@role='underline'">
      <fo:inline text-decoration="underline">
        <xsl:call-template name="inline.charseq"/>
      </fo:inline>
    </xsl:when>
    <xsl:when test="@role='strikethrough'">
      <fo:inline text-decoration="line-through">
        <xsl:call-template name="inline.charseq"/>
      </fo:inline>
    </xsl:when>
    <xsl:otherwise>
      <xsl:choose>
        <xsl:when test="$depth mod 2 = 1"><!--this is the line referenced in
the question-->
          <fo:inline font-style="normal">
            <xsl:apply-templates/>
          </fo:inline>
        </xsl:when>
        <xsl:otherwise>
          <xsl:call-template name="inline.italicseq"/>
        </xsl:otherwise>
      </xsl:choose>
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>