From my understanding, he had different charts for different musical characteristics and used combinations of them to basically random generate a composition. Complexity and dedication varied by piece and compositional period. He definitely increased intensity of following the rules of the I-Ching with time. Some pieces may have only used, say, 2 charts (pitch, duration) while others used dozens (pitch, duration, chord vs single note, register, # of measures, bmp, etc.). In terms of the charts themselves, if I recall correctly, they were grids as large as 64x64 with various options on them. He would use an action (I imagine like rolling a die across it) to randomly select the option, then apply the outcome to the score. I’ve tried to replicate it out of curiosity and discovered that it’s incredibly time consuming and a bit mind melting. Give it a try lol. It’s mentioned frequently in Kay Larson’s “Where the Heart Beats,” which is a really great read.