1 files changed, 4 insertions, 0 deletions
diff --git a/HACKING.md b/HACKING.md
index 3ac46cad..a961e2e4 100644
--- a/HACKING.md
+++ b/HACKING.md
@@ -9,6 +9,10 @@ Coding Style
 * Follow the style guide for python code:
     http://www.python.org/dev/peps/pep-0008/
 * Test the code with "doctest" where it makes sense
+* when breaking backward compatibility with old configuration files or plugins,
+  please include a temporary workaround code that provides a compatibility
+  layer and mark it with a comment that includes the word "COMPAT".  For
+  examples, grep the code for the word "COMPAT". :)
 
 
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