diff --git a/data/boxes.csv b/data/boxes.csv
index 721ee3f..f07d23b 100644
--- a/data/boxes.csv
+++ b/data/boxes.csv
@@ -281,3 +281,4 @@ elng,Extended Language Tag,ISO
 rsot,Redundant Sample Original Timing,ISO
 ssrt,Sub-sample Reference Table Box,ISO
 mini,The MinimizedImageBox provides a more compact representation of the MetaBox for a subset of use cases,HEIF
+ctlc,Content Type for Loudness Control,