+#
+# 'D' (Dynamic) allows the use of variables. Supported variables are:
+# $host, $origin (the IP address the request came from), $path and $url.
+#
+# Note that '$' is a bad choice as delimiter for dynamic filters as you
+# might end up with unintended variables if you use a variable name
+# directly after the delimiter. Variables will be resolved without
+# escaping anything, therefore you also have to be careful not to chose
+# delimiters that appear in the replacement text. For example '<' should
+# be save, while '?' will sooner or later cause conflicts with $url.