diff --git a/requirements.md b/requirements.md
index cca9e66..5c85e9b 100644
--- a/requirements.md
+++ b/requirements.md
@@ -100,5 +100,15 @@
 - The `{secondary element}` is `{secondary association}` the
   `{primary element}`.
 
+These correspond to the mapper D-Bus object paths
+`{primary element}/{primary assocation}` with an endpoints property value of
+`{secondary element}` and `{secondary element}/{secondary association}` with an
+endpoints property value of `{primary element}`.
+
 In some cases it may be required for grammatical correctness to add a
-preposition to the secondary assocation, such as 'by' or 'with'.
+preposition to the secondary association, such as 'by' or 'with'.
+
+Additional information on associations is in the [mapper documentation][].
+
+[mapper documentation]:
+  https://github.com/openbmc/docs/blob/master/architecture/object-mapper.md#associations