diff --git a/tox.ini b/tox.ini
index 4f695b420b..55d7a7abbb 100644
--- a/tox.ini
+++ b/tox.ini
@@ -26,6 +26,11 @@ setenv = VIRTUAL_ENV={envdir}
          NOSE_COVER_HTML=1
          NOSE_COVER_HTML_DIR={toxinidir}/cover
 
+# Since the practice demonstrated that developers keep adding py2-specific
+# code inadvertedly, we instituted a practice of "py3 ratchet": we convert
+# tests file by file, add them into the list below, and never go back.
+# This list also serves as a shared task board for those helping with py3.
+# But mind that reviews expanding this list may be outstanding in Gerrit.
 [testenv:py35]
 commands =
   nosetests {posargs:\