diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 7bf6467b54..7c7a2dc80e 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -3341,6 +3341,33 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-SDKMACHINE'><glossterm>SDKMACHINE</glossterm>
+            <glossdef>
+                <para>
+                    The architecture of the machine that runs Application
+                    Development Toolkit (ADT) items.
+                    In other words, packages are built so that they will run
+                    on the target you specify with the argument.
+                    This implies that you can build out ADT/SDK items that
+                    run on an architecture other than that of your build host.
+                    For example, you can use an x86_64-based build host to
+                    create packages that will run on an i686-based
+                    SDK Machine.
+                </para>
+
+                <para>
+                    You can use "i686" and "x86_64" as possible values for this
+                    variable.
+                    The variable defaults to "i686" and is set in the
+                    <filename>local.conf</filename> file in the
+                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
+                    <literallayout class='monospaced'>
+     SDKMACHINE ?= "i686"
+                    </literallayout>
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-SECTION'><glossterm>SECTION</glossterm>
             <glossdef>
                 <para>The section in which packages should be categorized.