diff --git a/circle.yml b/circle.yml
index 56dd43ce..0a2f638b 100644
--- a/circle.yml
+++ b/circle.yml
@@ -1,6 +1,6 @@
 machine:
   python:
-    version: 2.7.12
+    version: 2.7.12  # this specific version is preinstalled on the CI servers and allows faster builds
   env:
     PYPI_USERNAME: openfisca-bot  # set here the name of your Pypi account to automatically publish your template to Pypi
     # PYPI_PASSWORD: this value is set in CircleCI's web interface; do not set it here, it is a secret!
diff --git a/openfisca_country_template/parameters/__root__.xml b/openfisca_country_template/parameters/__root__.xml
index bb1402d0..28b87107 100644
--- a/openfisca_country_template/parameters/__root__.xml
+++ b/openfisca_country_template/parameters/__root__.xml
@@ -1 +1,4 @@
+<!-- Do not edit this file. -->
+
+<!-- Used to set up the XML tree and decrease nesting in other parameter files. -->
 <NODE code="root"/>