source of x,y coordinates in netlist.pb.txt and plc.get_node_width_height()?

I plotted the nodes from [Ariane RISC example netlist file](https://github.com/google-research/circuit_training/blob/c25b27b240468f307c3cacef4efd9cf1db9248f2/circuit_training/environment/test_data/ariane/netlist.pb.txt)

In summary:

- Parsed the netlist.pb.txt file using plc client.
- Got the canvas width and height with w,h = plc.get_canvas_width_height()
- Got the x,y coordinates of each node in the netlist with n_w, n_h = plc.get_node_width_height()
- Plotted each node on the canvas of size (w,h).

The resultant plot is:

Where the blue blocks are macros while the red blocks are clusters of standard cells. Can you please share what is the source of the coordinates of the nodes here?

Possibly the question is related to [issue #25](https://github.com/google-research/circuit_training/issues/25#issue-1268683034)

Start with the Ariane netlist.pb.txt file and the plc client entry points get_canvas_width_height() and get_node_width_height(). Trace where these values are populated, then document the coordinate source and how it relates to the plotted canvas; the issue is done when that explanation is available.

Written by the indexing model from the issue text.