Vol

The stochastic process is defined inside an input parameter of type Vol Spec.

If that process is multidimensional (driven by several risk factors) then the overall volatility is also multidimensional.

The type of volatility used here refers to a single component of the overall volatilty, in other words a volatility with respect to some single risk factor.

That risk factor is also specified in

Finally due to the several different ways that a volatility may be mathematically defined, the

More details on the mathematical definition of volatility can be found in