xsl:strip-space element is used at the top level of the stylesheet to define elements in the source
document for which white-space nodes are insignificant and should be removed from the tree before processing.
elements attribute is mandatory, and defines a space-separated list of element names.
The value "*" may be used to mean "all elements"; in this case any elements where whitespace is not
to be stripped may be indicated by an xsl:preserve-space element.