diff --git a/src/AbstractCleaner.php b/src/AbstractCleaner.php
index 8924294..2932297 100644
--- a/src/AbstractCleaner.php
+++ b/src/AbstractCleaner.php
@@ -91,6 +91,18 @@ abstract class AbstractCleaner
      */
     abstract public function values(): array;
 
+    /**
+     * Get all related values for a namespace from the cleaner.
+     *
+     * @param   string  $ns     The namespace
+     *
+     * @return  array<int,array<string,string>>     The values.
+     */
+    public function related(string $ns): array
+    {
+        return [];
+    }
+
     /**
      * Execute action on an value.
      *