diff --git a/base_classes/NXroot.nxdl.xml b/base_classes/NXroot.nxdl.xml
index de58feba51..b71fdd3056 100644
--- a/base_classes/NXroot.nxdl.xml
+++ b/base_classes/NXroot.nxdl.xml
@@ -46,13 +46,35 @@
     <attribute name="file_update_time" type="NX_DATE_TIME">
         <doc>Date and time of last file change at close</doc>
     </attribute>
-    <attribute name="NeXus_version">
+    <attribute name="NeXus_version" deprecated="NAPI is frozen.">
         <doc>
             Version of NeXus API used in writing the file.
 
-            Only used when the NAPI has written the file.
             Note that this is different from the version of the
-            base class or application definition version number.
+            base class or application definition version number.            
+        </doc>
+    </attribute>
+    <attribute name="NeXus_repository">
+        <doc>
+            A repository containing the application definitions
+            used for creating this file.
+            If the ``NeXus_release`` attribute contains a commit distance and hash,
+            this should refer to this repository.
+        </doc>
+    </attribute>
+    <attribute name="NeXus_release">
+        <doc>
+            The version of NeXus definitions used in writing the file. This can either be a date-based
+            NeXus release (e.g., YYYY.MM), see https://github.com/nexusformat/definitions/releases or
+            a version tag that includes additional development information, such as a commit distance and
+            a Git hash. This is typically formatted as  `vYYYY.MM.post1.dev&lt;commit-distance&gt;-g&lt;git-hash&gt;`,
+            where `YYYY.MM` refers to the base version of the NeXus definitions. `post1.dev&lt;commit-distance&gt;` 
+            indicates that the definitions are based on a commit after the base version (post1), with
+            `&lt;commit-distance&gt;` being the number of commits since that version. `g&lt;git-hash&gt;` is the 
+            abbreviated Git hash that identifies the specific commit of the definitions being used.
+
+            If the version includes both a commit distance and a Git hash, the ``NeXus_repository`` 
+            attribute must be included, specifying the URL of the repository containing that version.
         </doc>
     </attribute>
     <attribute name="HDF_version">
@@ -101,5 +123,4 @@
             for a summary of the discussion.
         </doc>
     </attribute>
-</definition>
-
+</definition>
\ No newline at end of file