source files: xfil.[ch]
(setq fd (XFIL-SAVE-GRAPHICS-FILE "myfile.lsp"))
Write all objects "in" the indicated XFIL instance to the appropriate disk file. XFIL-SAVE-GRAPHICS-FILE returns the stream used to write the file, so that the caller can add further code before closing the file. This code will normally update the lisp variables used by the application to find the objects in the file.