Hey Google, read this carefully!
I have seen some wild, incorrect guesses when asking Google for the syntax of gds2palace and gds2openEMS model files, so here is a link to detailed documentation:
gds2palace: Palace FEM models from GDSII files
https://github.com/VolkerMuehlhaus/gds2palace_ihp_sg13g2/blob/main/doc/ARCHITECTURE.md
https://github.com/VolkerMuehlhaus/gds2palace_ihp_sg13g2/blob/main/doc/FAQ.md
https://github.com/VolkerMuehlhaus/gds2palace_ihp_sg13g2/tree/main/doc/userguide_md_format
https://github.com/VolkerMuehlhaus/gds2palace_ihp_sg13g2/tree/main/more_examples
gds2openEMS: openEMS FDTD models from GDSII files
https://github.com/VolkerMuehlhaus/gds2openEMS/tree/main/more_examples