diff --git a/cs3/app/provider/v1beta1/provider_api.proto b/cs3/app/provider/v1beta1/provider_api.proto
index 84b0f525..85d0415a 100644
--- a/cs3/app/provider/v1beta1/provider_api.proto
+++ b/cs3/app/provider/v1beta1/provider_api.proto
@@ -89,12 +89,6 @@ message OpenInAppRequest {
   // The access token MUST be short-lived.
   // TODO(labkode): investigate token derivation techniques.
   string access_token = 4;
-  // OPTIONAL.
-  // A reference to the application to be used to open the resource, should the
-  // default inferred from the resource's mimetype be overridden by user's choice.
-  // If the targeted resource is a directory, this parameter is required and
-  // in its absence the implementation MUST return INVALID_ARGUMENT.
-  string app = 5;
 }
 
 message OpenInAppResponse {
diff --git a/cs3/gateway/v1beta1/gateway_api.proto b/cs3/gateway/v1beta1/gateway_api.proto
index 8e49fb78..ae815dda 100644
--- a/cs3/gateway/v1beta1/gateway_api.proto
+++ b/cs3/gateway/v1beta1/gateway_api.proto
@@ -550,8 +550,10 @@ message OpenInAppRequest {
   }
   ViewMode view_mode = 3;
   // OPTIONAL.
-  // The application to be used to open the resource. Defaults to the primary application
-  // registered for the mime type of the given resource.
+  // A reference to the application to be used to open the resource, should the
+  // default inferred from the resource's mimetype be overridden by user's choice.
+  // If the targeted resource is a directory, this parameter is required and
+  // in its absence the implementation MUST return INVALID_ARGUMENT.
   string app = 4;
 }
 
diff --git a/docs/index.html b/docs/index.html
index a7d4a8b4..cafc622f 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -2362,8 +2362,10 @@ <h3 id="cs3.gateway.v1beta1.OpenInAppRequest">OpenInAppRequest</h3>
                   <td><a href="#string">string</a></td>
                   <td></td>
                   <td><p>OPTIONAL.
-The application to be used to open the resource. Defaults to the primary application
-registered for the mime type of the given resource. </p></td>
+A reference to the application to be used to open the resource, should the
+default inferred from the resource&#39;s mimetype be overridden by user&#39;s choice.
+If the targeted resource is a directory, this parameter is required and
+in its absence the implementation MUST return INVALID_ARGUMENT. </p></td>
                 </tr>
               
             </tbody>
@@ -5187,17 +5189,6 @@ <h3 id="cs3.app.provider.v1beta1.OpenInAppRequest">OpenInAppRequest</h3>
 TODO(labkode): investigate token derivation techniques. </p></td>
                 </tr>
               
-                <tr>
-                  <td>app</td>
-                  <td><a href="#string">string</a></td>
-                  <td></td>
-                  <td><p>OPTIONAL.
-A reference to the application to be used to open the resource, should the
-default inferred from the resource&#39;s mimetype be overridden by user&#39;s choice.
-If the targeted resource is a directory, this parameter is required and
-in its absence the implementation MUST return INVALID_ARGUMENT. </p></td>
-                </tr>
-              
             </tbody>
           </table>
 
diff --git a/proto.lock b/proto.lock
index 686f67b7..31f6a23c 100644
--- a/proto.lock
+++ b/proto.lock
@@ -417,11 +417,6 @@
                 "id": 4,
                 "name": "access_token",
                 "type": "string"
-              },
-              {
-                "id": 5,
-                "name": "app",
-                "type": "string"
               }
             ]
           },