Tricky Metadata Problem

sorting-marc.xqy

xquery version "3.1";
declare namespace marc="http://www.loc.gov/MARC21/slim";

let $csv := element csv {
  let $records := fn:doc("https://raw.githubusercontent.com/sterkenburgsara/MARCXML-projects/master/Artists'%20Books/artistsbk.xml")//marc:collection/marc:record
  for $record in $records
  let $leader := $record/marc:leader/text()
  let $title :=
    ($record//marc:datafield[@tag='245']//text()
    except $record//marc:subfield[@code="c"]/text())
    => fn:string-join(" ")
    => fn:replace("/$", "")
    => fn:normalize-space()
    let $publoc :=
      let $control-8 := $record/marc:controlfield[@tag='008']/text()
      let $publoc := fn:substring($control-8,16,3)
      return $publoc
  let $csv-record :=
      element record {
        element leader {$leader},
        element title {$title},
        element publoc {$publoc}
    }
  where $publoc = ("alu", "aru", "dcu", "deu", "flu", "gau", "kyu", "lau", "mdu", "msu", "oku", "ncu", "scu", "tnu", "txu", "vau", "wvu", "xx ")
  order by $publoc  
  return$csv-record
}
return csv:serialize($csv, map {'header':true()})