I hope this helps,
Wendell

XML:

<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="example.xsl"?>
<example>
    <table desc="Example: 1 col table">
        <tr>
            <td col="1">col 1</td>
        </tr>
    </table>
    <table desc="Example: 2 col table">
        <tr>
            <td col="1">col 1</td>
            <td col="2">col 2</td>
        </tr>
    </table>
    <table desc="Example: 3 col table">
        <tr>
            <td col="1">col 1</td>
            <td col="2">col 2</td>
            <td col="3">col 2</td>
        </tr>
    </table>
</example>

XSL:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="1.0">
    <xsl:template match="table">
        <xsl:variable name="noofcols"  select="tr/td[last()]/@col"/>
        <table border="1">
            <tr>
                <td align="center"  colspan="{$noofcols}">
                    <xsl:value-of select="@desc"/>
                </td>
            </tr>
            <xsl:apply-templates select="tr"/>
        </table>
     </xsl:template>

    <xsl:template match="tr">
        <xsl:variable name="noofcols"
select="self::tr[1]/td[last()]/@col"/>
        <tr>
            <xsl:choose>
                <xsl:when test="$noofcols = 1">
                    <xsl:attribute name="bgcolor">red</xsl:attribute>
                </xsl:when>
                <xsl:otherwise>
                </xsl:otherwise>
            </xsl:choose>
            <xsl:apply-templates select="td"/>
        </tr>
    </xsl:template>

    <xsl:template match="td">
        <xsl:variable name="noofcols"
select="parent::tr[1]/td[last()]/@col"/>
        <td>
        <xsl:choose>
            <xsl:when test="$noofcols = 3">
                <xsl:attribute name="bgcolor">blue</xsl:attribute>
            </xsl:when>
        </xsl:choose>
        td col variable = <xsl:value-of select="$noofcols"/>
      </td>
    </xsl:template>

</xsl:stylesheet>

======================================================================
Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
Mulberry Technologies, Inc.                http://www.mulberrytech.com
17 West Jefferson Street                    Direct Phone: 301/315-9635
Suite 207                                          Phone: 301/315-9631
Rockville, MD  20850                                 Fax: 301/315-8285
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  Mulberry Technologies: A Consultancy Specializing in SGML and XML
======================================================================