GPL version 1 (or later). It is not considered part of GNU Emacs.
This version of the library differs from the original as described in
-the ChangeLog file. For example, the file "lwlib-int.h" was renamed
-from "lwlib-internal.h" in order to fit in 14 characters, and the
-makefile adjusted to fit in with Emacs's configure script.
+the ChangeLog.1 file.