diff --git a/core/nwb.base.yaml b/core/nwb.base.yaml
index 971a1a36..5da0e8c7 100644
--- a/core/nwb.base.yaml
+++ b/core/nwb.base.yaml
@@ -64,12 +64,11 @@ datasets:
 
 - neurodata_type_def: ExternalImage
   neurodata_type_inc: BaseImage
-  doc: A type for referencing an external image file.
-  attributes:
-  - name: file_path
-    dtype: text
-    doc: Path or URL to the external image file.
-    required: true
+  doc: A type for referencing an external image file. The single file path or URL to the external image file should
+    be stored in the dataset. This type should NOT be used if the image is stored 
+     in another NWB file and that file is linked to this file.
+  dtype: text
+  # shape: scalar  # this will be supported in the NWB schema language 2.0
 
 - neurodata_type_def: ImageReferences
   neurodata_type_inc: NWBData
diff --git a/docs/format/source/format_release_notes.rst b/docs/format/source/format_release_notes.rst
index 7904d441..26bd3fa3 100644
--- a/docs/format/source/format_release_notes.rst
+++ b/docs/format/source/format_release_notes.rst
@@ -8,7 +8,7 @@ Release Notes
 
 Major changes
 ^^^^^^^^^^^^^
-- Added `BaseImage` and `ExternalImage` as new neurodata types. The first so both `Image` and `ExternalImage` can inherit from it. The second to store external images (#604)
+- Added `BaseImage` and `ExternalImage` as new neurodata types. The first so both `Image` and `ExternalImage` can inherit from it. The second to store external images (#604, #623)
 
 Minor changes
 ^^^^^^^^^^^^^