+<p><li> Our POSIX policy: try to write code that only uses POSIX (IEEE
+Std 1003.1) interfaces and APIs. When you include <code>Rts.h</code>,
+<code>POSIX_SOURCE</code> is automatically defined for you before any
+system headers are slurped in, unless you define
+<code>NON_POSIX_SOURCE</code> prior to including <code>Rts.h</code>.
+A good C library will use the <code>POSIX_SOURCE</code> define to
+eliminate non-posix types and function prototypes, so the compiler
+should complain if you venture outside the POSIX spec.</li>
+
+<p><li>