The xsl:copy-of element copies of the value of the
expression in the mandatory select attribute to the result tree
If this expression is a string, a number, or a boolean, the effect is the same as using
xsl:sequence.
There is an optional attribute copy-namespaces whose value is "yes" or "no". The default
is "yes". This controls whether the in-scope namespaces of any element nodes copied by this instruction
are automatically copied to the result tree. If the value is "no", then namespaces will only be copied
if they are actually used in the names of elements or attributes. This allows you, for example, to
copy the contents of a SOAP message without copying the namespaces declared in its envelope.
