> <xsl:variable name="foo1"/>
>
>  <xsl:variable name="bar1" select= "'world'"/>
>
>
>  <xsl:value-of select="($foo,$bar)[1]"/> <!--first-->
>
>    <xsl:value-of select="(string($foo1),$bar1)[1]"/><!--Second-->
>
> First worked but second did not work
> I was expecting "World" to be output to the result ..

Oh no, string($foo1) gives you an empty string, which is a valid first member
of the sequence, so that is what you get.

- Michael