Connecting to Two Web Parts with a Different Parameter for Each

Had a solution requiring a single drop-down list in a dataview web part to filter the contents of two other data view web parts, each of which required a different field as the input parameter - i.e. the Controls web part was to be filtered by Control Refs and the Gaps web parts was to be filtered by Gap Refs. The two fields (Control Refs and Gap Refs) are multi-select lookup columns in the Risks list.

After much experimentation (and a fair bit of cursing!), I found the answer.

The dropdown dataview uses the following code for each row. The important points to note are the concatenation of the two required field values in the fields variable, and the concatenation of the two consumer GUIDs in the GenFireCOnnection call.

<option>
    <xsl:attribute name="value">
        <xsl:variable name="cursel">dvt_curselkey={<xsl:call-template name="dvt.gencurselkey"><xsl:with-param name="RowPath" select="." /></xsl:call-template>}</xsl:variable>
        <xsl:variable name="fields">@Control_x0020_Refs=<xsl:value-of select="ddwrt:ConnEncode(string(@Control_x0020_Refs))" />#@Gap_x0020_Refs0=<xsl:value-of select="ddwrt:ConnEncode(string(@Gap_x0020_Refs0))" /></xsl:variable>
        <xsl:text>javascript:</xsl:text>
        <xsl:value-of select="ddwrt:GenFireConnection( concat( 'g_1a7694bc_1a99_427e_aece_bcbfdf0ba2b9#g_c79865fa_2833_4543_aefe_0a8f466211aa*', $fields),string($cursel))"></xsl:value-of>
        <xsl:text>;</xsl:text>
    </xsl:attribute>
    <xsl:if test="$dvt_curselkey=@ID">
        <xsl:attribute name="selected">true</xsl:attribute>
    </xsl:if>
    <xsl:value-of select="@Risk_x0020_Ref" /> - <xsl:value-of select="@Title" />
</option>