diff --git a/TODO b/TODO
index c9f5a8537c1..b213586530b 100644
--- a/TODO
+++ b/TODO
@@ -130,6 +130,9 @@ Deprecations and removals:
 
 Features:
 
+* add a new specifier to unit files that figures out the DDI the unit file is
+  from, tracing trough overlayfs, DM, loopback block device.
+
 * in os-release define a field that can be initialized at build time from
   SOURCE_DATE_EPOCH (maybe even under that name?). Would then be used to
   initialize the timestamp logic of ConditionNeedsUpdate=.