Not exactly, although it has some similarities. If I understood José correctly, his theory is that the internal reservoir of each color on the Pro-1000, has 2 sensors, One sensor on top marks full level (of the internal reservoir, not the cartridge) and the other sensor located at the bottom of that reservoir signals 'low'. He compares this system to the flush of a toilet.
When the level of ink in the reservoir reaches the bottom sensor, a valve connecting the cart with this reservoir is opened to admit ink from the cart, until the level in the reservoir reaches the top sensor and then the valve is closed.
If there’s not enough ink left in the cart to fill the reservoir up to the top sensor, then the printer knows that the cart. is empty.