File: Data.xml
File: Query.xquery
declare namespace functx = "http://www.rntsoft.com";
declare function functx:min-non-empty-string
($stringSeq as xs:string*) as xs:string? {
min($stringSeq[. != ''])
};
(: Example call :)
functx:min-non-empty-string(doc("Data.xml")//car/@model)
Output:
A