Returns an xs:QName with the namespace URI given in $paramURI.
If $paramURI is the zero-length string or the empty sequence, it
represents "no namespace"; in this case, if the value of $paramQName
contains a colon (:), an error is raised [err:FOCA0002].
The prefix (or absence of a prefix) in $paramQName is retained in
the returned xs:QName value. The local name in the result is taken
from the local part of $paramQName.
If $paramQName does not have the correct lexical form for
xs:QName an error is raised [err:FOCA0002].
Note that unlike xs:QName this function does not require an
xs:string literal as the argument.
fn.QName("http://www.example.com/example", "person")
=> an xs:QName with namespace URI =
"http://www.example.com/example",
local name = "person", and
prefix = "".
fn.QName("http://www.example.com/example", "ht:person")
=> an xs:QName with namespace URI =
"http://www.example.com/example",
local name = "person",
and prefix = "ht".