diff --git a/fixtures/3/accompanyingCanvas.json b/fixtures/3/accompanyingCanvas.json
new file mode 100644
index 0000000..641259e
--- /dev/null
+++ b/fixtures/3/accompanyingCanvas.json
@@ -0,0 +1,81 @@
+{
+  "@context": "http://iiif.io/api/presentation/3/context.json",
+  "id": "https://iiif.io/api/cookbook/recipe/0014-accompanyingcanvas/manifest.json",
+  "type": "Manifest",
+  "label": {
+    "en": [
+      "Partial audio recording of Gustav Mahler's _Symphony No. 3_"
+    ]
+  },
+  "items": [
+    {
+      "id": "https://iiif.io/api/cookbook/recipe/0014-accompanyingcanvas/canvas/p1",
+      "type": "Canvas",
+      "label": {
+        "en": [
+          "Gustav Mahler, Symphony No. 3, CD 1"
+        ]
+      },
+      "duration": 1985.024,
+      "accompanyingCanvas": {
+        "id": "https://iiif.io/api/cookbook/recipe/0014-accompanyingcanvas/canvas/accompanying",
+        "type": "Canvas",
+        "label": {
+          "en": [
+            "First page of score for Gustav Mahler, Symphony No. 3"
+          ]
+        },
+        "height": 998,
+        "width": 772,
+        "items": [
+          {
+            "id": "https://iiif.io/api/cookbook/recipe/0014-accompanyingcanvas/canvas/accompanying/annotation/page",
+            "type": "AnnotationPage",
+            "items": [
+              {
+                "id": "https://iiif.io/api/cookbook/recipe/0014-accompanyingcanvas/canvas/accompanying/annotation/image",
+                "type": "Annotation",
+                "motivation": "painting",
+                "body": {
+                  "id": "https://iiif.io/api/image/3.0/example/reference/4b45bba3ea612ee46f5371ce84dbcd89-mahler-0/full/,998/0/default.jpg",
+                  "type": "Image",
+                  "format": "image/jpeg",
+                  "height": 998,
+                  "width": 772,
+                  "service": [
+                    {
+                      "id": "https://iiif.io/api/image/3.0/example/reference/4b45bba3ea612ee46f5371ce84dbcd89-mahler-0",
+                      "type": "ImageService3",
+                      "profile": "level1"
+                    }
+                  ]
+                },
+                "target": "https://iiif.io/api/cookbook/recipe/0014-accompanyingcanvas/canvas/accompanying"
+              }
+            ]
+          }
+        ]
+      },
+      "items": [
+        {
+          "id": "https://iiif.io/api/cookbook/recipe/0014-accompanyingcanvas/canvas/page/p1",
+          "type": "AnnotationPage",
+          "items": [
+            {
+              "id": "https://iiif.io/api/cookbook/recipe/0014-accompanyingcanvas/canvas/page/annotation/segment1-audio",
+              "type": "Annotation",
+              "motivation": "painting",
+              "body": {
+                "id": "https://fixtures.iiif.io/audio/indiana/mahler-symphony-3/CD1/medium/128Kbps.mp4",
+                "type": "Sound",
+                "duration": 1985.024,
+                "format": "video/mp4"
+              },
+              "target": "https://iiif.io/api/cookbook/recipe/0014-accompanyingcanvas/canvas/page/p1"
+            }
+          ]
+        }
+      ]
+    }
+  ]
+}
\ No newline at end of file
diff --git a/fixtures/3/placeholderCanvas.json b/fixtures/3/placeholderCanvas.json
new file mode 100644
index 0000000..6cf6568
--- /dev/null
+++ b/fixtures/3/placeholderCanvas.json
@@ -0,0 +1,68 @@
+{
+  "@context": "http://iiif.io/api/presentation/3/context.json",
+  "id": "https://iiif.io/api/cookbook/recipe/0013-placeholderCanvas/manifest.json",
+  "type": "Manifest",
+  "label": {
+    "en": [
+      "Video recording of Donizetti's _The Elixer of Love_"
+    ]
+  },
+  "items": [
+    {
+      "id": "https://iiif.io/api/cookbook/recipe/0013-placeholderCanvas/canvas/donizetti",
+      "type": "Canvas",
+      "duration": 7278.466,
+      "width": 640,
+      "height": 360,
+      "placeholderCanvas": {
+        "id": "https://iiif.io/api/cookbook/recipe/0013-placeholderCanvas/canvas/donizetti/placeholder",
+        "type": "Canvas",
+        "width": 640,
+        "height": 360,
+        "items": [
+          {
+            "id": "https://iiif.io/api/cookbook/recipe/0013-placeholderCanvas/canvas/donizetti/placeholder/1",
+            "type": "AnnotationPage",
+            "items": [
+              {
+                "id": "https://iiif.io/api/cookbook/recipe/0013-placeholderCanvas/canvas/donizetti/placeholder/1-image",
+                "type": "Annotation",
+                "motivation": "painting",
+                "body": {
+                  "id": "https://fixtures.iiif.io/video/indiana/donizetti-elixir/act1-thumbnail.png",
+                  "type": "Image",
+                  "format": "image/png",
+                  "width": 640,
+                  "height": 360
+                },
+                "target": "https://iiif.io/api/cookbook/recipe/0013-placeholderCanvas/canvas/donizetti/placeholder"
+              }
+            ]
+          }
+        ]
+      },
+      "items": [
+        {
+          "id": "https://iiif.io/api/cookbook/recipe/0013-placeholderCanvas/donizetti/1",
+          "type": "AnnotationPage",
+          "items": [
+            {
+              "id": "https://iiif.io/api/cookbook/recipe/0013-placeholderCanvas/donizetti/1-video",
+              "type": "Annotation",
+              "motivation": "painting",
+              "body": {
+                "id": "https://fixtures.iiif.io/video/indiana/donizetti-elixir/vae0637_accessH264_low.mp4",
+                "type": "Video",
+                "duration": 7278.466,
+                "width": 640,
+                "height": 360,
+                "format": "video/mp4"
+              },
+              "target": "https://iiif.io/api/cookbook/recipe/0013-placeholderCanvas/canvas/donizetti"
+            }
+          ]
+        }
+      ]
+    }
+  ]
+}
\ No newline at end of file
diff --git a/schema/iiif_3_0.json b/schema/iiif_3_0.json
index 17bf5ca..1a8dfc4 100644
--- a/schema/iiif_3_0.json
+++ b/schema/iiif_3_0.json
@@ -424,6 +424,8 @@
                         "seeAlso": { "$ref": "#/classes/seeAlso" },
                         "services": { "$ref": "#/classes/service" },
                         "service": { "$ref": "#/classes/service" },
+                        "placeholderCanvas": { "$ref": "#/classes/placeholderCanvas" },
+                        "accompanyingCanvas": { "$ref": "#/classes/accompanyingCanvas" },
                         "thumbnail": {
                             "type": "array",
                             "items": { "$ref": "#/classes/resource" }
@@ -489,6 +491,8 @@
                         "service": { "$ref": "#/classes/service" },
                         "services": { "$ref": "#/classes/service" },
                         "viewingDirection": { "$ref": "#/classes/viewingDirection" },
+                        "placeholderCanvas": { "$ref": "#/classes/placeholderCanvas" },
+                        "accompanyingCanvas": { "$ref": "#/classes/accompanyingCanvas" },
                         "rights": { "$ref": "#/classes/rights" },
                         "start": {},
                         "navDate": { "$ref": "#/classes/navDate" },
@@ -605,6 +609,8 @@
                         "provider": { "$ref": "#/classes/provider" },
                         "seeAlso": { "$ref": "#/classes/seeAlso" },
                         "service": { "$ref": "#/classes/service" },
+                        "placeholderCanvas": { "$ref": "#/classes/placeholderCanvas" },
+                        "accompanyingCanvas": { "$ref": "#/classes/accompanyingCanvas" },
                         "thumbnail": {
                             "type": "array",
                             "items": { "$ref": "#/classes/resource" }
@@ -638,6 +644,124 @@
                 }
             ]
         },
+        "placeholderCanvas": {
+            "allOf": [
+                { "$ref": "#/types/class" },
+                {
+                    "type": "object",
+                    "properties": {
+                        "type": {
+                            "type": "string",
+                            "pattern": "^Canvas$",
+                            "default": "Canvas"
+                        },
+                        "height": { "$ref": "#/types/dimension" },
+                        "width": { "$ref": "#/types/dimension" },
+                        "duration": { "$ref": "#/types/duration" },
+                        "metadata": { "$ref": "#/classes/metadata" },
+                        "summary": { "$ref": "#/types/lngString" },
+                        "requiredStatement": { "$ref": "#/types/keyValueString" },
+                        "rendering": { "$ref": "#/types/external" },
+                        "rights": { "$ref": "#/classes/rights" },
+                        "navDate": { "$ref": "#/classes/navDate" },
+                        "navPlace": { "$ref": "#/classes/navPlace" },
+                        "provider": { "$ref": "#/classes/provider" },
+                        "seeAlso": { "$ref": "#/classes/seeAlso" },
+                        "service": { "$ref": "#/classes/service" },
+                        "thumbnail": {
+                            "type": "array",
+                            "items": { "$ref": "#/classes/resource" }
+                        },
+                        "homepage": { "$ref": "#/classes/homepage" },
+                        "behavior": { "$ref": "#/classes/behavior" },
+                        "partOf": { "$ref": "#/classes/partOf" },
+                        "items": {
+                            "type": "array",
+                            "items": {
+                                "$ref": "#/classes/annotationPage"
+                            }
+                        },
+                        "annotations": {
+                            "type": "array",
+                            "items": {
+                                "$ref": "#/classes/annotationPage"
+                            }
+                        }
+                    },
+                    "required": ["items"],
+                    "anyOf":[
+                        { "required": ["width"] },
+                        { "required": ["height"] },
+                        { "required": ["duration"] }
+                    ],
+                    "dependencies": {
+                        "width": ["height"],
+                        "height": ["width"]
+                    },
+                    "not": { "required": [ "placeholderCanvas", "accompanyingCanvas" ] }
+                }
+            ]
+        },
+        "accompanyingCanvas": {
+            "allOf": [
+                { "$ref": "#/types/class" },
+                {
+                    "type": "object",
+                    "properties": {
+                        "type": {
+                            "type": "string",
+                            "pattern": "^Canvas$",
+                            "default": "Canvas"
+                        },
+                        "height": { "$ref": "#/types/dimension" },
+                        "width": { "$ref": "#/types/dimension" },
+                        "duration": { "$ref": "#/types/duration" },
+                        "metadata": { "$ref": "#/classes/metadata" },
+                        "summary": { "$ref": "#/types/lngString" },
+                        "requiredStatement": { "$ref": "#/types/keyValueString" },
+                        "rendering": { "$ref": "#/types/external" },
+                        "rights": { "$ref": "#/classes/rights" },
+                        "navDate": { "$ref": "#/classes/navDate" },
+                        "navPlace": { "$ref": "#/classes/navPlace" },
+                        "provider": { "$ref": "#/classes/provider" },
+                        "seeAlso": { "$ref": "#/classes/seeAlso" },
+                        "service": { "$ref": "#/classes/service" },
+                        "thumbnail": {
+                            "type": "array",
+                            "items": { "$ref": "#/classes/resource" }
+                        },
+                        "homepage": { "$ref": "#/classes/homepage" },
+                        "behavior": { "$ref": "#/classes/behavior" },
+                        "partOf": { "$ref": "#/classes/partOf" },
+                        "items": {
+                            "type": "array",
+                            "items": {
+                                "$ref": "#/classes/annotationPage"
+                            }
+                        },
+                        "annotations": {
+                            "type": "array",
+                            "items": {
+                                "$ref": "#/classes/annotationPage"
+                            }
+                        }
+                    },
+                    "required": ["items"],
+                    "anyOf":[
+                        { "required": ["width"] },
+                        { "required": ["height"] },
+                        { "required": ["duration"] }
+                    ],
+                    "dependencies": {
+                        "width": ["height"],
+                        "height": ["width"]
+                    },
+                    "not": { "required": [ "placeholderCanvas", "accompanyingCanvas" ] }
+                }
+            ]
+        },
+
+
         "annotationCollection": {
             "allOf": [
                 { "$ref": "#/types/class" },
@@ -848,6 +972,8 @@
                         "rendering": { "$ref": "#/types/external" },
                         "supplementary": { "$ref": "#/classes/annotationCollection" },
                         "service": { "$ref": "#/classes/service" },
+                        "placeholderCanvas": { "$ref": "#/classes/placeholderCanvas" },
+                        "accompanyingCanvas": { "$ref": "#/classes/accompanyingCanvas" },
                         "annotations": {
                             "type": "array",
                             "items": {
diff --git a/tests/test_validator.py b/tests/test_validator.py
index c3bba34..44feb14 100644
--- a/tests/test_validator.py
+++ b/tests/test_validator.py
@@ -146,7 +146,9 @@ def test07_check_manifest3(self):
                      'fixtures/3/publicdomain.json',
                      'fixtures/3/navPlace.json',
                      'fixtures/3/anno_source.json',
-                     'fixtures/3/range_range.json'
+                     'fixtures/3/range_range.json',
+                     'fixtures/3/accompanyingCanvas.json',
+                     'fixtures/3/placeholderCanvas.json'
                      ]:
             with open(good, 'r') as fh:
                 print ('Testing: {}'.format(good))