PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT ?name ?mbox (STRDT("iiii", <http://example/romanNumeral>) as ?strdt) (STRLANG("chat", "en") as ?strlang) (uuid() as ?uuid) (STRUUID() as ?struuid)
WHERE {
    ?x foaf:name  ?name ;
       foaf:mbox  ?mbox .
    FILTER isIRI(?mbox)
    FILTER isBlank(?mbox)
    FILTER isLiteral(?mbox)
    FILTER isNumeric(?mbox)
    FILTER STR(?mbox)
    FILTER LANG(?mbox)
    FILTER DATATYPE(?mbox)
    FILTER IRI(?mobox)
    FILTER BNODE("string")
}