And here are the different sizes and configurations
This circuit uses the Infield Pits with T1 at the upper left end of the straight.
The Inner and Outer circuits can run independently from their own pits, the Inner circuit runs anti/counter clockwise while the outer runs clockwise.
There are 3 short circuits combinations that can run independently of each other, however one doesn't have a pit complex and would be used as a driving school only.
The Three short circuit can be combined into three National or International race circuits whilst still allowing one of the three to operate independently.