diff --git a/docs/protocol.md b/docs/protocol.md
index a0725b2..660f3c0 100644
--- a/docs/protocol.md
+++ b/docs/protocol.md
@@ -69,7 +69,7 @@ Every message has a `type`. The first is always `hello`.
     { "index": 0, "short_name": "county", "kind": "p25", "config": { "apiKey": "…" } },
     { "index": 1, "short_name": "city", "kind": "p25", "config": { "apiKey": "…" },
       "settings": { "server": "https://openmhz.example.org" } },
-    { "index": 65535, "short_name": "conv", "kind": "conventional", "config": null }
+    { "index": 2, "short_name": "conv", "kind": "conventional", "config": null }
   ],
   "capture_dir": "/home/me/TrunkRecorderPro",
   "data_dir": "/home/me/.config/trunk-pro/plugin-data/openmhz",
diff --git a/docs/settings.md b/docs/settings.md
index 0edc406..ffabe10 100644
--- a/docs/settings.md
+++ b/docs/settings.md
@@ -163,7 +163,10 @@ So don't key anything you save on it, such as calls queued for a later run.
 `setup.system_named(name)` finds a system by short name.
 
 Each conventional system is a system of its own, with its own short name and
-settings.
+settings. Systems are numbered from 0, trunked first, then conventional; tell
+a conventional one by its `kind` (`"conventional"`), not by its number. (Before
+Trunk Recorder Pro v0.1.16, conventional systems were numbered down from 65535
+and the SDK had a `CONVENTIONAL` constant; SDK 0.5.0 drops it.)
 
 ## Settings a system overrides