diff --git a/source/content/cookies.md b/source/content/cookies.md
index 40d78950e1..6e3d120c26 100644
--- a/source/content/cookies.md
+++ b/source/content/cookies.md
@@ -57,7 +57,15 @@ if (isset($_SERVER['PANTHEON_ENVIRONMENT'])) {
 
 ## Cache-Varying Cookies
 
-Respond to a request with cached content depending on the presence and value of a particular cookie. It's important to note that in order for the response to be cached by Pantheon's Edge, the cookie name must match `STYXKEY[a-zA-Z0-9_-]+`.
+Respond to a request with cached content depending on the presence and value of a particular cookie. It's important to note that in order for the response to be cached by Pantheon's Edge, the cookie name must follow these naming rules:
+* Must begin with the 7 capital letters `STYXKEY`
+* Must have one or more of the following:
+	* letters `a-z` and `A-Z`
+	* numbers `0-9`
+	* underscore `_`
+	* hyphen `-`
+
+If you prefer a regular expression, the name must match the following format: `STYXKEY[a-zA-Z0-9_-]+`. Test your cookie with [Regex 101.](https://regex101.com/) 
 
 First, check to see if the cookie is set within the incoming request. If the cookie is set, store the value and use it to generate varied content as appropriate for your use case and implementation.