diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index fc95845c66..01f5fe9cfb 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -1695,6 +1695,32 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-LINUX_VERSION_EXTENSION'><glossterm>LINUX_VERSION_EXTENSION</glossterm>
+            <glossdef>
+                <para>A string extension compiled into the name of the
+                    Linux kernel built with the OpenEmbedded build system.
+                    You define this variable in the kernel recipe.
+                    For example, the <filename>linux-yocto-custom.bb</filename>
+                    kernel recipe found in
+                    <filename>meta-skeleton/recipes-kernel/linux</filename>
+                    defines the variable as follows:
+                    <literallayout class='monospaced'>
+     LINUX_VERSION_EXTENSION ?= "-custom"
+                    </literallayout>
+                    Defining this variable essentially sets the
+                    Linux kernel configuration item
+                    <filename>CONFIG_LOCALVERSION</filename>, which is visible
+                    through the <filename>uname</filename> command.
+                    Here is an example that shows the extension assuming it
+                    was set as previously shown:
+                    <literallayout class='monospaced'>
+     $ uname -r
+     3.7.0-rc8-custom
+                    </literallayout>
+                </para>
+            </glossdef>
+        </glossentry>
+
     </glossdiv>
 
     <glossdiv id='var-glossary-m'><title>M</title>