diff --git a/cleverhans/picklable_model.py b/cleverhans/picklable_model.py
index <HASH>..<HASH> 100644
--- a/cleverhans/picklable_model.py
+++ b/cleverhans/picklable_model.py
@@ -1,5 +1,11 @@
-"""Models that support pickling
-
+"""Models that support pickling.
+
+NOTE: This module is much more free to change than many other modules
+in CleverHans. CleverHans is very conservative about changes to any
+code that affects the output of benchmark tests (attacks, evaluation
+methods, etc.). This module provides *models* not *benchmarks* and
+thus is free to change rapidly to provide better speed, accuracy,
+etc.
 """
 
 from __future__ import absolute_import
diff --git a/cleverhans/train.py b/cleverhans/train.py
index <HASH>..<HASH> 100644
--- a/cleverhans/train.py
+++ b/cleverhans/train.py
@@ -1,3 +1,14 @@
+"""
+Multi-replica synchronous training
+
+
+NOTE: This module is much more free to change than many other modules
+in CleverHans. CleverHans is very conservative about changes to any
+code that affects the output of benchmark tests (attacks, evaluation
+methods, etc.). This module provides *model training* functionality
+not *benchmarks* and thus is free to change rapidly to provide better
+speed, accuracy, etc.
+"""
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
disclaimers about fast-changing portions of codebase