
The xquery_eval function returns the result of applying the xquery expression to the
context node.  By default only the first result is returned, but supplying a third argument
allows you to specify an index for the value, the default assumes a value of 1 here.
A value of 0 returns an array of 0 or more elements, one for each value calculated by the
xquery expression.
	
When an entity is returned in a result set to a client the client will see an nvarchar value containing the
serialization of the entity, complete with markup.
When the entity is passed as a SQL value it remains
an entity referencing the node of a parsed XML tree, permitting navigation inside the tree.
	