diff --git a/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst b/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
index f20a9012c..6612dcc03 100644
--- a/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
+++ b/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
@@ -1071,6 +1071,28 @@ overview of their function and contents.
          When specifying a directory name, use the trailing slash character
          to ensure you match just that directory name.
 
+      .. note::
+
+         The leading slash in a regular expression in :term:`BBMASK` does not
+         mean the path is absolute. It simply forces the directory to be named
+         exactly that. Take::
+
+            BBMASK = "meta-ti/recipes-bsp/"
+
+        If you happen to have a directory ``my-meta-ti/recipes-bsp``, it will
+        be matched.
+
+        Leading with a slash::
+
+           BBMASK = "/meta-ti/recipes-bsp/"
+
+        makes sure that doesn't happen. However, this doesn't prevent matching a
+        directory ``meta-foo/meta-ti/recipes-bsp``. For that, use the
+        appropriate :term:`BBFILE_PATTERN` to only match a directory from one
+        specific layer::
+
+           BBMASK = "${BBFILE_PATTERN_meta-ti}/recipes-bsp/"
+
    :term:`BBMULTICONFIG`
       Enables BitBake to perform multiple configuration builds and lists
       each separate configuration (multiconfig). You can use this variable