My extracted spice file looks like below , with not so friendly names for nets (my be by default) , how do i customized the instance and net names ? * SPICE3 file created from inverter2.ext - technology: sky130B .subckt sky130_fd_pr__pfet_01v8_2ZVKGK a_15_n42# a_n15_n68# a_n73_n42# VSUBS X0 a_15_n42# a_n15_n68# a_n73_n42# w_n109_n104# sky130_fd_pr__pfet_01v8 ad=1.218e+11p pd=1.42e+06u as=1.218e+11p ps=1.42e+06u w=420000u l=150000u .ends .subckt sky130_fd_pr__nfet_01v8_FNPZCM a_15_n42# a_n15_n68# a_n73_n42# VSUBS X0 a_15_n42# a_n15_n68# a_n73_n42# VSUBS sky130_fd_pr__nfet_01v8 ad=1.218e+11p pd=1.42e+06u as=1.218e+11p ps=1.42e+06u w=420000u l=150000u .ends .subckt inverter2 VDD VSS OUT IN Xsky130_fd_pr__pfet_01v8_2ZVKGK_0 OUT IN VDD VSUBS sky130_fd_pr__pfet_01v8_2ZVKGK Xsky130_fd_pr__nfet_01v8_FNPZCM_0 OUT IN VSS VSUBS sky130_fd_pr__nfet_01v8_FNPZCM .ends

Looks like you're using parameterized nfets and pfets. Flattening these cells in the layout may give you a cleaner extraction, but have the drawback of not being able to modify the parameters easily later. See https://skywater-pdk.slack.com/archives/C016YSAP6TZ/p1644998694479219

@User: Magic's default net name is the layer and position of the lower-left corner of the lowest layer of the net. Magic's default instance name is the cell name plus an underscore plus an integer starting with zero. Both can be renamed by editing a layout and using "identify <name>" on a selected instance to change the instance name, or by adding a label to change a net name. Because these are parameterized cells, those changes will only remain if you don't try to edit the parameters and update the cell view, but as long as you don't touch the cell, they will remain. It would probably be a good idea to add labels, at least on device ports (source, drain, gate, . . . ) in the parameterized cell drawing routines.