Answers to the above questions (copied from the google groups email): (1) There are no rules about special distancing for NxN contacts. Everything you need to know about the DRC rules should be found here: https://skywater-pdk--136.org.readthedocs.build/en/136/rules/periphery.html#m4 (2) "periphery" is apparently a concept rolled over from Cypress. Of course, Cypress is known for memory chips and IP. In this terminology, "core" refers to a core SRAM (or other memory) block, and "periphery" is everything outside of that. (3) The "core" rules (e.g., memory cell rules) are usually called out separately as exceptions for "areaid.ce" or for specific cell names. (3a) Yes. Enclosure rules are either for all sides or for opposite sides. (4) The "_C" refers to a conformal dielectric, one which is related to a specific layer (usually metal) either by growing from the sidewalls or both the sidewalls and top. (5) Most strange geometries like this one show up in the seal ring and nowhere else (rule mcon.3: "Only min. square mcons are allowed except die seal ring. . . ").