diff --git a/Design:-Persistable-Context.md b/Design:-Persistable-Context.md
index f89e7be..7689047 100644
--- a/Design:-Persistable-Context.md
+++ b/Design:-Persistable-Context.md
@@ -29,6 +29,9 @@ If you want to access the external storage, add the prefix(*) to the key of cont
 
   If prefix is not added, data in current local memory is accessed.
 
+
+> NOL: I am concerned that using `$` is too close to environment variable syntax. Having played with a few alternatives, I propose `#` as the prefix. Please let me know what you think.
+
 ### how to use in function node
 ![function](https://github.com/node-red-hitachi/node-red/wiki/images/inFunction.png)