diff --git a/application/migrations/090_make_mode_frequency_null.php b/application/migrations/090_make_mode_frequency_null.php
index af2d4aa3..6d8a332e 100644
--- a/application/migrations/090_make_mode_frequency_null.php
+++ b/application/migrations/090_make_mode_frequency_null.php
@@ -5,7 +5,8 @@ defined('BASEPATH') OR exit('No direct script access allowed');
 /**
  * Class Migration_make_mode_frequency_null
  *
- * Creates a varchar column in CAT table that holds value of propagation mode
+ * Modify frequency and mode column so that NULL is allowed
+ * Basically for propmode != SAT
  * 
  */