@Mohammad Mudakir Fazili: It appears that the "core" rules (called "core" because the process comes from Cypress, and their business was making memory chips, so the memory is considered the "core" and everything else is the "periphery") are completely missing from the open PDK online documentation. I'm not sure how that happened (you can try submitting an issue on the github issue tracker for skywater-pdk, if there isn't an issue for it already).