diff --git a/Design:-Custom-Node-admin-route-handling.md b/Design:-Custom-Node-admin-route-handling.md
index 3c1deeb..703ec11 100644
--- a/Design:-Custom-Node-admin-route-handling.md
+++ b/Design:-Custom-Node-admin-route-handling.md
@@ -9,6 +9,9 @@ This poses some problems for the split of the editor and runtime.
 
 One of the goals of the split is to be able to serve the editor from a static file server (eg AWS S3) and point it at a server hosting the admin api. At this point, any relative urls a custom node uses will break - as they will be relative to the S3 url, not the admin api url.
 
+### Editor side
+
+
 There are a number of ways a user may access these custom routes - each needs a slightly different solution.
 
 | Type of route | Resolution |
@@ -23,9 +26,23 @@ There are a number of ways a user may access these custom routes - each needs a
 | `<link>` inside edit template `<script>`  | As with `<script>`, but this happens each time the edit dialog is opened for a node. |
 | **Adding images to the page** | |
 | `<img>` in edit template | As with `<script>`, but this happens each time the edit dialog is opened for a node. |
-| Dynamically added via code | We cannot intercept these - no good solution to keep things working as it |
+| Dynamically added via code | We cannot intercept these - no good solution to keep things working as-is |
 
 
-So we can cover a number of the cases via code inspection and url rewriting - but not all. I don't know how common it is for nodes to add custom images - but its possible to do so.
+So we can cover a number of the cases via code inspection and url rewriting - but not all. I don't know how common it is for nodes to add custom images - but its possible, so needs to be handled.
+
+### Runtime side
+
+With the split, the server side splits into two separate modules:
+ - The runtime module is where nodes are registered and live.
+ - The editor module provides the admin express app to expose the admin routes on an http server instance
+
+with the new runtime-api used as the interface between them.
+
+By splitting them like that, a node can no longer have direct access to the admin express app instance. Which is a *big* problem.
+
+On the whole, they just add routes using the standard `app.get/post/del/put` functions. But some will do something more involved, such as add an instance of serveStatic (or similar) to serve up static content for the node, or allowing file upload.
+
+To achieve a full split between the modules, the runtime-api needs to have some way of abstracting out these routes so they can be made over RPC. *There's no nice way of doing that*.