HtmlTableAccessibility

The following XSL customization inserts the headers attribute in HTML table cells. It only supports header rows, not row headers in one of the columns.

Sample DocBook XML

<informaltable tabstyle="content">

• <tgroup cols="4">

  • <colspec colwidth="630*" colname="col1" /> <colspec colwidth="2970*" colname="col2" /> <colspec colwidth="1350*" colname="col3" /> <colspec colwidth="3240*" colname="col4" /> <thead>

    • <row>

      • <entry colname="col1">

        • <para role="atgtablebody">A</para>

        </entry> <entry colname="col2">

        • <para role="atgtablebody">Quick Brown Fox Jumps</para>

        </entry> <entry colname="col3">

        • <para role="atgtablebody">Over</para>

        </entry> <entry colname="col4">

        • <para role="atgtablebody">The Lazy Dog</para>

        </entry>

      </row>

    </thead> <tbody>

    • <row>

      • <entry colname="col1">

        • <para role="atgtablebody">B</para>

        </entry> <entry colname="col2">

        • <para role="atgtablebody">How high?</para>

        </entry> <entry colname="col3">

        • <para role="atgtablebody">Under</para>

        </entry> <entry colname="col4">

        • <para role="atgtablebody">The long day</para>

        </entry>

      </row> <row>

      • <entry colname="col1">

        • <para role="atgtablebody">C</para>

        </entry> <entry colname="col2">

        • <para role="atgtablebody">Why?</para>

        </entry> <entry colname="col3">

        • <para role="atgtablebody">Through</para>

        </entry> <entry colname="col4">

        • <para role="atgtablebody">The leering dentist</para>

        </entry>

      </row>

    </tbody>

  </tgroup>

</informaltable>

Customized DocBook XSL

<xsl:template match="d:entry|d:entrytbl" name="entry">

• [snip]

  <xsl:if test="$charoff != ">

  • <xsl:attribute name="charoff">

    • <xsl:value-of select="$charoff"/>

    </xsl:attribute>

  </xsl:if>

  <xsl:choose>

  • <xsl:when test="$cellgi = 'th'">

    • <xsl:attribute name="id">

      • <xsl:text>colhead</xsl:text> <xsl:value-of select="generate-id()"/>

      </xsl:attribute>

    </xsl:when> <xsl:when test="$cellgi = 'td'">

    • <xsl:if test="ancestor::*[@tabstyle='content']">

      • <xsl:attribute name="headers">

        • <xsl:choose>

          • <xsl:when test="@colname">

            • <xsl:call-template name="findHeaderCell">

              • <xsl:with-param name="colname" select="@colname" />

              </xsl:call-template>

            </xsl:when> <xsl:when test="@nameend">

            • <xsl:call-template name="findMultipleHeaderCells">

              • <xsl:with-param name="namest" select="@namest" /> <xsl:with-param name="nameend" select="@nameend" />

              </xsl:call-template>

            </xsl:when> <xsl:otherwise>

            • <xsl:message>ERROR: attempting to add a headers attribute to a table cell that has no colname or nameend attribute.</xsl:message>

            </xsl:otherwise>

          </xsl:choose>

        </xsl:attribute>

      </xsl:if>

    </xsl:when> <xsl:otherwise>

    • <xsl:message>ERROR: The cell type <xsl:value-of select="$cellgi" /> is neither th nor td.</xsl:message>

    </xsl:otherwise>

  </xsl:choose> [snip]

</xsl:template>

<xsl:template name="findHeaderCell">

• <xsl:param name="colname" /> <xsl:choose>

  • <xsl:when test="../../../d:thead/d:row/d:entry[@colname=$colname]">

    • <xsl:text>colhead</xsl:text> <xsl:value-of select="generate-id(../../../d:thead/d:row/d:entry[@colname=$colname])"/>

    </xsl:when> <xsl:when test="../../../d:thead/d:row/d:entry[@namest=$colname]">

    • <xsl:text>colhead</xsl:text> <xsl:value-of select="generate-id(../../../d:thead/d:row/d:entry[@namest=$colname])"/>

    </xsl:when> <xsl:when test="../../../d:colspec[@colname=$colname]">

    • <xsl:apply-templates select="../../../d:colspec[@colname=$colname]" mode="findColspecWithMatch" />

    </xsl:when> <xsl:otherwise>

    • <xsl:message>ERROR: No table header cells nor colspecs match the current table body cell. My value is: <xsl:value-of select="."/></xsl:message>

    </xsl:otherwise>

  </xsl:choose>

</xsl:template>

<xsl:template name="findMultipleHeaderCells">

• <xsl:param name="namest" /> <xsl:param name="nameend" /> <xsl:param name="currentColname" select="$nameend" /> <xsl:param name="previousMatches" /> <!-- Find the header cell for the current column. Write its value. --> <xsl:variable name="newValue">

  • <xsl:call-template name="findHeaderCell">

    • <xsl:with-param name="colname" select="$currentColname" />

    </xsl:call-template> <xsl:text> </xsl:text> <xsl:value-of select="$previousMatches" />

  </xsl:variable>

  <!-- If the currentColname does not match the namest, find the colspec element

  • preceding the one that has a colname matching the currentColname. Call this

    template with its colname in the currentColname param. -->

  <xsl:choose>

  • <xsl:when test="$currentColname != $namest">

    • <xsl:call-template name="findMultipleHeaderCells">

      • <xsl:with-param name="currentColname">

        • <xsl:apply-templates select="../../../d:colspec[@colname=$currentColname]" mode="findPrecedingColname" />

        </xsl:with-param> <xsl:with-param name="namest" select="$namest" /> <xsl:with-param name="nameend" select="$nameend" /> <xsl:with-param name="previousMatches" select="$newValue" />

      </xsl:call-template>

    </xsl:when> <xsl:otherwise>

    • <xsl:value-of select="$newValue" />

    </xsl:otherwise>

  </xsl:choose>

</xsl:template>

Sample HTML Output