Couple questions about the Grid

Hi, I have a couple of questions about the grid -

1. The grid lists a bunch of systems with sub fees of zero $, yet when I went to look at the pages for those systems many of them had healthy fees. Why is the grid info inaccurate or out of date?

2. Are the grid metrics defined anywhere? Some are well known but for example how exactly are "C2 score", "hidden risk", etc calculated?

TIA for any / all answers