diff --git a/docs/drivers/MTConnect.md b/docs/drivers/MTConnect.md
index 4756c00a..47e0c7c7 100644
--- a/docs/drivers/MTConnect.md
+++ b/docs/drivers/MTConnect.md
@@ -180,7 +180,13 @@ into) is resolved in this order, first non-null wins:
 
 1. The `RawTags[]` blob's `driverDataType` or `dataType` field (both
    spellings accepted — the typed editor writes `dataType`, the driver's own
-   `tags[]` shape uses `driverDataType`).
+   `tags[]` shape uses `driverDataType`). **`driverDataType` wins when it is
+   non-blank**, and a present-but-invalid one rejects the tag rather than
+   falling through to `dataType`. The AdminUI's typed editor mirrors that
+   precedence on load and **normalises onto `dataType`, dropping the alias, on
+   save** (Gitea #550) — so a tag edited through the editor keeps the type the
+   driver read for it, and an unreadable spelling is refused at authoring
+   instead of dying at the driver.
 2. A matching `Tags[]` entry naming the same DataItem id.
 3. The Agent's own `/probe` declaration, via `MTConnectDataTypeInference.Infer`
    (category/type/units/representation → `DriverDataType`).