1 files changed, 2 insertions, 0 deletions
diff --git a/RULES b/RULES
index 457923f..398b2e5 100644
--- a/RULES
+++ b/RULES
@@ -56,6 +56,8 @@
 	   other blocks to populate themselves with higher readability.
 	   Refer to RULE 5-4.
 
+2.7. Do not refer to (or declare as a child) a block that does not exist
+	in this repository.
 
 
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