diff --git a/regression_tests/ref_counter.jl b/regression_tests/ref_counter.jl
index b763073bad..8a6a898e3b 100644
--- a/regression_tests/ref_counter.jl
+++ b/regression_tests/ref_counter.jl
@@ -1,5 +1,24 @@
 179
 
+# **README**
+#
+# What is the ref_counter?
+#
+# The ref_counter is part of reproduciability tests. The counter identifies a
+# particular snapshot of our code, a "reference". Each PR is tested against this
+# reference to check if it reproduces the expected behavior. This allows us to
+# check that PRs that are expected to not modify the behavior do indeed preserve
+# the previous behavior.
+#
+# When am I allowed to increase the ref_counter?
+#
+# If know that your PR is changing some behavior (e.g., you are changing
+# parameters, or how things are computed, or added a new component), you should
+# increase the number on top of this file and add an explanation on why it has
+# changed in the comments below. Increasing the ref_counter will make your PR
+# the new reference that other PRs will be compared against.
+
+
 #=
 179:
 - Update Pi entr groups/ add parameter vectors