LibreDWG
GNU LibreDWG is a software library programmed in C to manage DWG computer files , native proprietary format of computer-aided design software AutoCAD . 
<triplet> LibreDWG <subj> software library <obj> instance of <subj> C <obj> programming language <subj> DWG <obj> readable file format <triplet> DWG <subj> proprietary format <obj> subclass of <triplet> AutoCAD <subj> DWG <obj> writable file format <subj> computer-aided design <obj> use