why is -9 good practice rather that -188 or -123.456, or, as in the
posted code, -0.5 ? what is so special about -9 that you say it _should_
be used?

 >
 > Saxon will say Recoverable Error if two template match the same node.

sorry, I thought
<xsl:template match="@*|node()">
and
<xsl:template match="*[not(node())]" />
have the same default priority

But there was no other templates of the same priority in the supplied code.

David