1 files changed, 14 insertions, 0 deletions
diff --git a/iseq.h b/iseq.h
index 3f3ed8a195..5c55aa0e40 100644
--- a/iseq.h
+++ b/iseq.h
@@ -151,7 +151,21 @@ struct iseq_catch_table_entry {
 	CATCH_TYPE_REDO   = INT2FIX(5),
 	CATCH_TYPE_NEXT   = INT2FIX(6)
     } type;
+    
+    /*
+     * iseq type:
+     *   CATCH_TYPE_RESCUE, CATCH_TYPE_ENSURE:
+     *     use iseq as continuation.
+     *
+     *   CATCH_TYPE_BREAK (iter):
+     *     use iseq as key.
+     *
+     *   CATCH_TYPE_BREAK (while), CATCH_TYPE_RETRY,
+     *   CATCH_TYPE_REDO, CATCH_TYPE_NEXT:
+     *     NULL.
+     */
     const rb_iseq_t *iseq;
+
     unsigned int start;
     unsigned int end;
     unsigned int cont;