diff --git a/Documentation/README.html b/Documentation/README.html
index 1a814b5f29..aecabdc7ae 100644
--- a/Documentation/README.html
+++ b/Documentation/README.html
@@ -8,7 +8,7 @@
   <tr align="center" bgcolor="#e4e4e4">
     <td>
       <h1><big><font color="#3c34ec"><i>NuttX README Files</i></font></big></h1>
-      <p>Last Updated: May 24, 2018</p>
+      <p>Last Updated: May 29, 2018</p>
     </td>
   </tr>
 </table>
@@ -385,16 +385,17 @@ nuttx/
  |       `- <a href="https://bitbucket.org/nuttx/nuttx/src/master/fs/unionfs/README.txt" target="_blank"><b><i>README.txt</i></b></a>
  |- graphics/
  |   `- <a href="https://bitbucket.org/nuttx/nuttx/src/master/graphics/README.txt" target="_blank"><b><i>README.txt</i></b></a>
- |- lib/
- |   `- <a href="https://bitbucket.org/nuttx/nuttx/src/master/lib/README.txt" target="_blank">README.txt</a>
- |- libc/
- |   |- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libc/zoneinfo/README.txt" target="_blank">zoneinfo/README.txt</a>
- |   `- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libc/README.txt" target="_blank"><b><i>README.txt</i></b></a>
- |- libnx/
- |   |- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libnx/nxfonts/README.txt" target="_blank">libnx/README.txt</a>
- |   `- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libnx/README.txt" target="_blank"><b><i>README.txt</i></b></a>
- |- libxx/
- |   `- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libxx/README.txt" target="_blank"><b><i>README.txt</i></b></a>
+ |-libs
+ |   |- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libs/README.txt" target="_blank">README.txt</a>
+ |   |- libc/
+ |   |   |- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libs/libc/zoneinfo/README.txt" target="_blank">zoneinfo/README.txt</a>
+ |   |   `- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libs/libc/README.txt" target="_blank"><b><i>README.txt</i></b></a>
+ |   |- libnx/
+ |   |   |- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libs/libnx/nxfonts/README.txt" target="_blank">libnx/README.txt</a>
+ |   |   `- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libs/libnx/README.txt" target="_blank"><b><i>README.txt</i></b></a>
+ |   |- libxx/
+ |   |   `- <a href="https://bitbucket.org/nuttx/nuttx/src/master/libs/libxx/README.txt" target="_blank"><b><i>README.txt</i></b></a>
+
  |- mm/
  |   |- shm/
  |   |   `- <a href="https://bitbucket.org/nuttx/nuttx/src/master/mm/shm/README.txt" target="_blank"><b><i>README.txt</i></b></a>
diff --git a/README.txt b/README.txt
index 59e1078f2c..5aca4d83b0 100644
--- a/README.txt
+++ b/README.txt
@@ -1975,17 +1975,17 @@ nuttx/
  |       `- README.txt
  |- graphics/
  |   `- README.txt
- |- lib/
- |   `- README.txt
- |- libc/
- |   |- zoneinfo
+ |- libs/
+ |   |- README.txt
+ |   |- libc/
+ |   |   |- zoneinfo
+ |   |   |   `- README.txt
  |   |   `- README.txt
- |   `- README.txt
- |- libnx/
- |   |- nxfongs
+ |   |- libnx/
+ |   |   |- nxfongs
+ |   |   |   `- README.txt
  |   |   `- README.txt
- |   `- README.txt
- |- libxx/
+ |   |- libxx/
  |   `- README.txt
  |- mm/
  |   |- shm/
diff --git a/libs/README.txt b/libs/README.txt
new file mode 100644
index 0000000000..c751de17fe
--- /dev/null
+++ b/libs/README.txt
@@ -0,0 +1,25 @@
+README
+======
+
+This directory holds NuttX libraries.  Libraries in NuttX are very special
+creatures.  The have these properties:
+
+1. They can be shared by both application logic and logic within the OS when
+   using the FLAT build.
+
+2. But in PROTECTED and KERNEL modes, they must be built differently:  The
+   copies used by applications and the OS cannot be the same.  Rather,
+   separate versions of libraries must be built for the kernel and for
+   applications.
+
+3. When used by the OS, some special care must be taken to assure that the
+   OS logic does not disrupt the user's errno value and that the OS does
+   not create inappropriate cancellation points.
+ 
+   For example, sem_wait() is both a cancellation point and modifies the
+   errno value.  So within the FLAT build and without kernel version for
+   the PROTECTED and KERNEL builds, the special internal OS interface
+   nxsem_wait() must be used.  Within libraries, the macro  _SEM_WAIT()
+   (as defined in include/nuttx/semaphore.h) is used instead.  The
+   definition of this macro accounts for the different usage environments.
+