bug or wrong way for VALUES in SPARQL, OpenLink Virtuoso?

问题

I have Virtuoso 7.10 and command VALUES works for 1*x or x*1 asign to tables like:

SELECT * WHERE 
{
VALUES (?z ?r ?t)
{
 ("x" "y" "z")
}
}

and for:

SELECT * WHERE 
{
VALUES ?z
{
 "x" "y" "z"
}
}

But the problem is when i try to assign like this:

SELECT * WHERE 
{
VALUES (?z ?r ?t)
{
 ("x" "y" "z")
 ("xy" "yx" "zx")
}
}

then in result, i have only first column filled, but other two are empty (same as with two column). Is it a bug or am I doing something wrong? Is there a workaround?

来源：https://stackoverflow.com/questions/26732902/bug-or-wrong-way-for-values-in-sparql-openlink-virtuoso