diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index cf69d5a86c..26a5aed827 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -1358,13 +1358,32 @@ system and gives an overview of their function and contents.
       speed since the build system skips parsing recipes not compatible
       with the current machine.
 
+      If one wants to have a recipe only available for some architectures
+      (here ``aarch64`` and ``mips64``), the following can be used::
+
+         COMPATIBLE_MACHINE = "^$"
+         COMPATIBLE_MACHINE:arch64 = "^(aarch64)$"
+         COMPATIBLE_MACHINE:mips64 = "^(mips64)$"
+
+      The first line means "match all machines whose :term:`MACHINEOVERRIDES`
+      contains the empty string", which will always be none.
+
+      The second is for matching all machines whose :term:`MACHINEOVERRIDES`
+      contains one override which is exactly ``aarch64``.
+
+      The third is for matching all machines whose :term:`MACHINEOVERRIDES`
+      contains one override which is exactly ``mips64``.
+
+      The same could be achieved with::
+
+         COMPATIBLE_MACHINE = "^(aarch64|mips64)$"
+
       .. note::
 
          When :term:`COMPATIBLE_MACHINE` is set in a recipe inherits from
          native, the recipe is always skipped. All native recipes must be
          entirely target independent and should not rely on :term:`MACHINE`.
 
-
    :term:`COMPLEMENTARY_GLOB`
       Defines wildcards to match when installing a list of complementary
       packages for all the packages explicitly (or implicitly) installed in