> >    <xsl:if at-at-least-one-TASK-has-a-non-empty-DESCRIPTION>
> <xsl:if test="string(DESCRIPTION)">

Oh, sorry, I missed the "if at-least-one ..."
What I gave you was "if this TASK ..."
Try this:

<xsl:if test="../TASK[string(DESCRIPTION)]">

It will be true if this node-set is not empty:

child elements of the parent node of the current node
 that are named TASK
 and for which this is true:
   there is a not-null string value of the
   DESCRIPTION child element of the current node


 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list