diff --git a/include/libg1m/format/cas.h b/include/libg1m/format/cas.h
index 070be1a..920485e 100644
--- a/include/libg1m/format/cas.h
+++ b/include/libg1m/format/cas.h
@@ -81,6 +81,10 @@ struct cas40 {
  * using the CAS50 name, which was more appropriate.
  * Notice that most headers the Graph 100 (~2002) still used CAS40.
  *
+ * The main differences between CAS40 and CAS50 are:
+ * - CAS50 has a more `struct`-ural approach (no specific subheader);
+ * - CAS50 include the app you're interacting with.
+ *
  * The header format is the following: */
 
 struct cas50 {