diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 0000000..f0b054f
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,17 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [ 
+    { 
+        "type": "node", 
+        "request": "launch", 
+        "name": "Jasmine Tests", 
+         "program": "${workspaceFolder:rpde-validator}/node_modules/jasmine/bin/jasmine.js", 
+        "env": { 
+            "NODE_PATH": "." 
+        } 
+   }
+]
+}
\ No newline at end of file
diff --git a/src/rules/page/required-property-values-rule.js b/src/rules/page/required-property-values-rule.js
index 1b0dbc2..36d5b5c 100644
--- a/src/rules/page/required-property-values-rule.js
+++ b/src/rules/page/required-property-values-rule.js
@@ -13,8 +13,18 @@ const RequiredPropertyValuesRule = class extends RpdeRule {
       description: 'Validates that the feed properties conform to the correct format',
       tests: {
         state: {
-          description: 'Raises a failure if the state property isn\'t one of "updated" or "deleted"',
-          message: 'The [`state` property](https://www.openactive.io/realtime-paged-data-exchange/#-item-) must be of value "updated" or "deleted", but was found to be different in {{count}} items in the feed.',
+          description: 'Raises a failure if the `state` property isn\'t one of "updated" or "deleted"',
+          message: 'The [`state` property](https://www.openactive.io/realtime-paged-data-exchange/#-state-) must be of value "updated" or "deleted", but was found to be different in {{count}} items in the feed.',
+          sampleValues: {
+            count: 23,
+          },
+          category: ValidationErrorCategory.CONFORMANCE,
+          severity: ValidationErrorSeverity.FAILURE,
+          type: RpdeErrorType.INVALID_FORMAT,
+        },
+        id: {
+          description: 'Raises a failure if the `id` property isn\'t a string or an integer in any item',
+          message: 'The [`id` property](https://www.openactive.io/realtime-paged-data-exchange/#-id-) must be a string, but was found to be different in {{count}} items in the feed.',
           sampleValues: {
             count: 23,
           },
@@ -23,8 +33,18 @@ const RequiredPropertyValuesRule = class extends RpdeRule {
           type: RpdeErrorType.INVALID_FORMAT,
         },
         kind: {
-          description: 'Raises a failure if the kind property isn\'t a string in any item',
-          message: 'The [`kind` property](https://www.openactive.io/realtime-paged-data-exchange/#-item-) must be a string, but was found to be different in {{count}} items in the feed.',
+          description: 'Raises a failure if the `kind` property isn\'t a string in any item',
+          message: 'The [`kind` property](https://www.openactive.io/realtime-paged-data-exchange/#-kind-) must be a string, but was found to be different in {{count}} items in the feed.',
+          sampleValues: {
+            count: 23,
+          },
+          category: ValidationErrorCategory.CONFORMANCE,
+          severity: ValidationErrorSeverity.FAILURE,
+          type: RpdeErrorType.INVALID_FORMAT,
+        },
+        data: {
+          description: 'Raises a failure if the `data` property isn\'t an object in any item',
+          message: 'The [`data` property](https://www.openactive.io/realtime-paged-data-exchange/#-data-) must be an object, but was found to be different in {{count}} items in the feed.',
           sampleValues: {
             count: 23,
           },
@@ -114,6 +134,8 @@ const RequiredPropertyValuesRule = class extends RpdeRule {
       state: 0,
       kind: 0,
       item: 0,
+      id: 0,
+      data: 0,
     };
 
     if (node.data.items instanceof Array) {
@@ -142,6 +164,18 @@ const RequiredPropertyValuesRule = class extends RpdeRule {
         ) {
           invalidProps.kind += 1;
         }
+        if (
+          typeof item.id !== 'undefined'
+          && typeof item.id !== 'string' && typeof item.id !== 'number'
+        ) {
+          invalidProps.id += 1;
+        }
+        if (
+          typeof item.data !== 'undefined'
+          && (typeof item.data !== 'object' || item.data instanceof Array)
+        ) {
+          invalidProps.data += 1;
+        }
       }
     }
 
diff --git a/src/rules/page/required-property-values-rule.spec.js b/src/rules/page/required-property-values-rule.spec.js
index 08bba07..840d623 100644
--- a/src/rules/page/required-property-values-rule.spec.js
+++ b/src/rules/page/required-property-values-rule.spec.js
@@ -64,6 +64,60 @@ describe('RequiredPropertyValuesRule', () => {
     }
   });
 
+  it('should raise an error when the id field is not a string or integer', () => {
+    json.items[0].id = [];
+    const node = new RpdeNode(
+      url,
+      json,
+      log,
+    );
+
+    rule.validate(node);
+
+    expect(log.addPageError).toHaveBeenCalled();
+    expect(log.pages.length).toBe(1);
+    expect(log.pages[0].errors.length).toBe(1);
+    for (const error of log.pages[0].errors) {
+      expect(error.type).toBe(RpdeErrorType.INVALID_FORMAT);
+    }
+  });
+
+  it('should raise an error when the data field is not an object', () => {
+    json.items[0].data = [];
+    const node = new RpdeNode(
+      url,
+      json,
+      log,
+    );
+
+    rule.validate(node);
+
+    expect(log.addPageError).toHaveBeenCalled();
+    expect(log.pages.length).toBe(1);
+    expect(log.pages[0].errors.length).toBe(1);
+    for (const error of log.pages[0].errors) {
+      expect(error.type).toBe(RpdeErrorType.INVALID_FORMAT);
+    }
+  });
+
+  it('should raise an error when the kind field is not a string', () => {
+    json.items[0].kind = 123;
+    const node = new RpdeNode(
+      url,
+      json,
+      log,
+    );
+
+    rule.validate(node);
+
+    expect(log.addPageError).toHaveBeenCalled();
+    expect(log.pages.length).toBe(1);
+    expect(log.pages[0].errors.length).toBe(1);
+    for (const error of log.pages[0].errors) {
+      expect(error.type).toBe(RpdeErrorType.INVALID_FORMAT);
+    }
+  });
+
   it('should raise an error when the items field is not an array', () => {
     json.items = {};
     const node = new RpdeNode(
@@ -82,7 +136,7 @@ describe('RequiredPropertyValuesRule', () => {
     }
   });
 
-  it('should raise an error when there is an item field that is not an object', () => {
+  it('should raise an error when there is an items field that is not an object', () => {
     json.items[0] = 1234;
     const node = new RpdeNode(
       url,