1 files changed, 9 insertions, 2 deletions
diff --git a/src/data/things/additional-file.js b/src/data/things/additional-file.js
index 398d0af5..b15f62e0 100644
--- a/src/data/things/additional-file.js
+++ b/src/data/things/additional-file.js
@@ -2,10 +2,9 @@ import {input} from '#composite';
 import Thing from '#thing';
 import {isString, validateArrayItems} from '#validators';
 
-import {contentString, simpleString, thing} from '#composite/wiki-properties';
-
 import {exposeConstant, exposeUpdateValueOrContinue}
   from '#composite/control-flow';
+import {contentString, simpleString, thing} from '#composite/wiki-properties';
 
 export class AdditionalFile extends Thing {
   static [Thing.getPropertyDescriptors] = () => ({
@@ -26,6 +25,14 @@ export class AdditionalFile extends Thing {
         value: input.value([]),
       }),
     ],
+
+    // Expose only
+
+    isAdditionalFile: [
+      exposeConstant({
+        value: input.value(true),
+      }),
+    ],
   });
 
   static [Thing.yamlDocumentSpec] = {