Sure, but that's very general and only fits certain circumstances.
For example if you have:
<xsl:template match="foo">
<span style="background:blue">
<xsl:apply-templates/>
</span>
</xsl:template>
..in your html-producing stylesheet and a corresponding
template in your fo-producing stylesheet, what happens when
its decided the background should be red?
How can we arrange it so that change from blue to red is made
in one place rather than both stylesheets?
What's wrong with a global variable?
<xsl:variable name="foo-background" select="'blue'"/>
<xsl:template match="foo">
<span style="background:{$foo-background}">
Michael Kay
XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list