diff --git a/tests/README b/tests/README
index e52de8a5474683f71071a3e887c4062c52f9919b..6316d9369c5025b178d7d06d5cab4c046d09e00f 100644
--- a/tests/README
+++ b/tests/README
@@ -85,6 +85,19 @@ Data:
                of the ftp server. It uses a simple syntax that is left to
                describe here!
 
+TEST CASE NUMBERS
+
+ So far, I've used this system:
+
+ 1   -  99   HTTP
+ 100 - 199   FTP
+ 200 - 299   FILE
+ 300 - 399   HTTPS
+ 400 - 499   FTPS
+
+  ... if we run out of test numbers for a particular protocol, then we need
+  to fix it.
+
 TODO:
 
   * Make httpserver.pl work when we PUT without Content-Length: