diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index d5ca11b2a7..e0ceb43f21 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -1040,6 +1040,27 @@ Core layer for images cannot be removed
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-EXTENDPKGV'><glossterm>EXTENDPKGV</glossterm>
+            <glossdef>
+                <para>
+                    The full package version specification as it appears on the
+                    final packages produced by a recipe.
+                    The variable's value is normally used to fix a runtime
+                    dependency to the exact same version of another package
+                    in the same recipe:
+                    <literallayout class='monospaced'>
+     RDEPENDS_${PN}-additional-module = "${PN} (= ${EXTENDPKGV})"
+                    </literallayout>
+                </para>
+
+                <para>
+                    The dependency relationships are intended to force the
+                    package manager to upgrade these types of packages in
+                    lock-step.
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-EXTENDPE'><glossterm>EXTENDPE</glossterm>
             <glossdef>
                 <para>