diff --git a/graphics/composer/2.4/IComposerClient.hal b/graphics/composer/2.4/IComposerClient.hal
index 9e3cf0e..1a59bbd 100644
--- a/graphics/composer/2.4/IComposerClient.hal
+++ b/graphics/composer/2.4/IComposerClient.hal
@@ -34,7 +34,9 @@
         /**
          * The configuration group ID (as int32_t) this config is associated to.
          * Switching between configurations within the same group may be done seamlessly
-         * in some conditions via setActiveConfigWithConstraints.
+         * in some conditions via setActiveConfigWithConstraints. Configurations which
+         * share the same config group are similar in all attributes except for the
+         * vsync period.
          */
         CONFIG_GROUP = 7,
     };