source files: xfil.[ch]
Selects the named graphics file as the 'current file'. The named file must already exist -- the application must have previously either called XFIL-LOAD-GRAPHICS-FILE to load the file (or had the latter recursively load it), or else done a (send CLASS-GRAPHIC-FILE :new "myfile.lsp").
3D objects created will go in the named graphics file until a new 'current file' is selected, either by XFIL-SET-CURRENT-GRAPHICS-FILE or by creating/loading a new file.