Hello. I ran Magic DRC on npn_10p00x10p00 and it detected errors which is (probably) undefined in the PDK's documentation.

N-Diffusion to P-tap spacing < 0.33um across butted junction (PP.4b + NP.4c)

I think PP.4b is about the poly gate but there is no gate, and NP.4c is an undefined rule number ( https://gf180mcu-pdk.readthedocs.io/en/latest/physical_verification/design_manual/drm_07_09.html ). Where is "PP.4b + NP.4c" written?

This is a false positive error and the rule needs fixing.

@Tim Edwards Thanks, I will ignore this error.

Looking into the error in detail, it appears that the rule in the magic tech file was pulled from another tech file, but the rule does not apply for GF180MCU, and is invalid. I have removed it from the tech file so the error will go away in the future, but for now you can ignore it as you suggested.