I am always confused with multiple attribute clauses. For example:

> 
> ... a complete virtual system composed of virtualized hardware components onto which an unmodified operating system can be installed.
> 
> 
> 

For the "onto which an unmodified operating system call be installed." clause,
does the *which* point to *hardware components*
or *a complete virtual system*? 
Does the attribute clause always modify the nearest noun?