X ns-queries-results-q1:

<Q1> { for $n in distinct-values( for $i in (//* | //@*) return namespace-uri($i) ) return <ns>{$n}</ns> } </Q1>

 X ns-queries-results-q2:

declare namespace music = "http://www.example.org/music/records"; <Q2> { //music:title } </Q2>

 X ns-queries-results-q3:

declare namespace dt = "http://www.w3.org/2001/XMLSchema"; <Q3> { //*[@dt:*] } </Q3>

 X ns-queries-results-q4:

declare namespace xlink = "http://www.w3.org/1999/xlink"; <Q4 xmlns:xlink="http://www.w3.org/1999/xlink"> { for $hr in //@xlink:href return <ns>{ $hr }</ns> } </Q4>

 X ns-queries-results-q5:

declare namespace music = "http://www.example.org/music/records"; <Q5 xmlns:music="http://www.example.org/music/records"> { //music:record[music:remark/@xml:lang = "de"] } </Q5>

 X ns-queries-results-q6:

declare namespace ma = "http://www.example.com/AuctionWatch"; declare namespace anyzone = "http://www.example.com/auctioneers#anyzone"; <Q6 xmlns:ma="http://www.example.com/AuctionWatch"> { //ma:Auction[@anyzone:ID]/ma:Schedule/ma:Close } </Q6>

 X ns-queries-results-q7:

declare namespace ma = "http://www.example.com/AuctionWatch"; <Q7 xmlns:xlink="http://www.w3.org/1999/xlink"> { for $a in //ma:Auction let $seller_id := $a/ma:Trading_Partners/ma:Seller/*:ID, $buyer_id := $a/ma:Trading_Partners/ma:High_Bidder/*:ID where namespace-uri(exactly-one($seller_id)) = namespace-uri($buyer_id) return $a/ma:AuctionHomepage } </Q7>

 X ns-queries-results-q8:

declare namespace ma = "http://www.example.com/AuctionWatch"; <Q8 xmlns:ma="http://www.example.com/AuctionWatch" xmlns:eachbay="http://www.example.com/auctioneers#eachbay" xmlns:xlink="http://www.w3.org/1999/xlink"> { for $s in //ma:Trading_Partners/(ma:Seller | ma:High_Bidder) where $s/*:NegativeComments = 0 return $s } </Q8>