diff --git a/docs/development/developer_faq.rst b/docs/development/developer_faq.rst
index 58f25506632..da321570894 100644
--- a/docs/development/developer_faq.rst
+++ b/docs/development/developer_faq.rst
@@ -2,6 +2,12 @@
 Developer FAQ
 *************
 
-
 Constants in TARDIS are all taken from Astropy. The module tardis.constants import all constants currently
 from astropy.constants.astropy13constants.
+
+Class design and inheritance:
+
+ * If only constructor changed -> use classmethod
+ * if overriding other methods -> subclass
+
+We use black to check PEP8 compliances.