script
Small standalone programs, in whatever language suited the job, called from the make targets in make/. Python where there is data to structure, perl where there is a text stream to rewrite.
They fall into three groups.
Check — turn a tool log into a verdict: checkant, checkkdrc, checklvs.
Fix — repair a netlist or a layout the tools got wrong: fixbbox, fixlpe, fixspi, fixsubckt.
Generate — write a file from another file: gensvinst, genver, genxdut, netlist_mdl.