The union between two sets is denoted with operator { , } .
Prototype
atvset <-- { set , set [ , set ]* }
Example
text( { {P, HEAD} , NOTE }, " "); P HEAD NOTEglobal $r = (first REF within file $myfile);
$r;<REF TARGET="note1"> (1) </REF>element REF attr: { attr($r) , PLACE="foot" } content: content($r) ;<REF TARGET="note1" PLACE="foot"> (1) </REF>