diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 04207acada..1cdf902d08 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -7209,9 +7209,13 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
         <glossentry id='var-TOPDIR'><glossterm>TOPDIR</glossterm>
             <glossdef>
                 <para>
-                    This variable points to the
+                    The top-level
                     <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
-                    BitBake automatically sets this variable.
+                    BitBake automatically sets this variable when you
+                    initialize your build environment using either
+                    <link linkend='structure-core-script'><filename>&OE_INIT_FILE;</filename></link>
+                    or
+                    <link linkend='structure-memres-core-script'><filename>oe-init-build-env-memres</filename></link>.
                 </para>
             </glossdef>
         </glossentry>