xsl:import element is always used at the top level of the stylesheet, and it must
appear before all other elements at the top level. It has a
href attribute, which is a URL (absolute or relative) of another stylesheet
to be textually included within this one. The top-level elements of the included stylesheet
effectively replace the xsl:import element.
xsl:import element may also be used at the top level of the included stylesheet, and so
The elements in the imported stylesheet have lower precedence than the elements in the
importing stylesheet. The main effect of this is on selection of a template when xsl:apply-templates
is used: if there is a matching template with precedence X, all templates with precedence less than
X are ignored, regardless of their priority.