[Discuss-gnuradio] What does complexity in Show Flowgraph Complexity in GRC means?

[Ignatius Rivaldi]

When I enabled Show Flowgraph Complexity in GRC, there is a small grey
box below the Options box with the writing Complexity: 564ubal. What
does that mean? What is ubal? Is higher slower? How high can I go?
Where is the documentation for that? I've tried googling 'gnuradio
flowgraph complexity'. 'gnuradio show flowgraph complexity' and
'gnuradio ubal' and there is no useful answers from all of those terms

Thanks