+* GNU/Linux development packages
+
+Many GNU/Linux systems do not come with development packages by
+default; they just include the files that you need to run Emacs, but
+not those you need to compile it. For example, to compile Emacs with
+X11 support, you may need to install the special `X11 development'
+package. For example, in April 2003, the package names to install
+were `XFree86-devel' and `Xaw3d-devel' on RedHat. On Debian, the
+packages necessary to build the installed version should be
+sufficient; they can be installed using `apt-get build-dep emacs21' in
+Debian 3 and above.