diff --git a/Documentation/md.txt b/Documentation/md.txt
index df0b455..4cf5972 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -302,6 +302,9 @@
 			 This includes spares that are in the process
 			 of being recoverred to
 	This list make grow in future.
+	This can be written to.
+	Writing "faulty"  simulates a failure on the device.
+	Writing "remove" removes the device from the array.
 
       errors
 	An approximate count of read errors that have been detected on