About LUBM generator

Question

When I make the data by LUBM generator, there are options however there is option called "-onto".

I got all the meaning of the options except that -onto options. I want to know about this option in details.

And secondly how can I test the queries in the LUBM ? Even if I read the tutorials, however I had no idea of the method of it.

If I can get the specific way, I'm glad.

Thanks.