diff --git a/doc/internals/key_format.mdwn b/doc/internals/key_format.mdwn
index f080552343..ac52bddea0 100644
--- a/doc/internals/key_format.mdwn
+++ b/doc/internals/key_format.mdwn
@@ -18,3 +18,6 @@ For example:
   This is currently only used by the WORM backend.
 * Other fields could be added in the future, if needed.
 * Fields may appear, in any order (though always before the name field).
+
+The `git annex examinekey` command can be used to extract information from
+a key.