Proposal: Add UUID field to multiscale objects

latest/examples/valid_strict/multiscales_example.json

@@ -2,6 +2,7 @@
     "multiscales": [
         {
             "version": "0.5-dev",
+            "uuid": "urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6",
             "name": "example",
             "axes": [
                 {"name": "t", "type": "time", "unit": "millisecond"},
@@ -51,4 +52,4 @@
             }
         }
     ]
-}
+}

latest/index.bs

@@ -288,14 +288,50 @@ It MAY contain exactly one `translation` that specifies the offset from the orig
 The length of the `scale` and `translation` array MUST be the same as the length of "axes".
 The requirements (only `scale` and `translation`, restrictions on order) are in place to provide a simple mapping from data coordinates to physical coordinates while being compatible with the general transformation spec.
 
-Each "multiscales" dictionary MAY contain the field "coordinateTransformations", describing transformations that are applied to all resolution levels in the same manner.
-The transformations MUST follow the same rules about allowed types, order, etc. as in "datasets:coordinateTransformations" and are applied after them.
-They can for example be used to specify the `scale` for a dimension that is the same for all resolutions.
-
-Each "multiscales" dictionary SHOULD contain the field "name". It SHOULD contain the field "version", which indicates the version of the multiscale metadata of this image (current version is [NGFFVERSION]).
-
-Each "multiscales" dictionary SHOULD contain the field "type", which gives the type of downscaling method used to generate the multiscale image pyramid.
-It SHOULD contain the field "metadata", which contains a dictionary with additional information about the downscaling method.
+Each "multiscales" dictionary:
+
+<ul>
+<li>
+   MAY contain the field "coordinateTransformations", describing transformations that are applied to all resolution levels in the same manner.
+   The transformations MUST follow the same rules about allowed types, order, etc. as in "datasets:coordinateTransformations" and are applied after them.
+   They can for example be used to specify the `scale` for a dimension that is the same for all resolutions.
+</li>
+
+<li>
+   SHOULD contain the field "name" which is informative to users but not sufficient for unique identifiation.
+</li>
+
+<li>
+  <p>
+   SHOULD contain the field "uuid" which is a
+   [RFC 4122](https://www.ietf.org/rfc/rfc4122.txt) compliant
+   string representation of a universally unique identifier,
+   e.g., "urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6" and SHOULD use
+   a compliant generator to minimize potential conflicts.
+  </p>
+  <p>
+  The uuid field is used to uniquely assign an identity to
+  objects in the dataset. Users MAY choose to store identical
+  objects, i.e. with the same uuid, in multiple filesets with
+  the intent that changes to either may eventually be applied
+  to all copies.
+  </p>
+</li>
+
+<li>
+   SHOULD contain the field "version", which indicates the version of the
+   multiscale metadata of this image (current version is [NGFFVERSION]).
+</li>
+
+<li>
+   SHOULD contain the field "type", which gives the type of downscaling method
+   used to generate the multiscale image pyramid.
+</li>
+
+<li>
+   SHOULD contain the field "metadata", which contains a dictionary with
+   additional information about the downscaling method.
+</li>
 
 <pre class=include-code>
 path: examples/valid_strict/multiscales_example.json

latest/schemas/image.schema

@@ -14,6 +14,9 @@
           "name": {
             "type": "string"
           },
+          "uuid": {
+            "type": "string"
+          },
           "datasets": {
             "type": "array",
             "minItems": 1,

latest/schemas/strict_image.schema

@@ -9,11 +9,11 @@
         "multiscales": {
           "items": {
             "required": [
-              "version", "metadata", "type", "name"
+              "version", "metadata", "type", "name", "uuid"
             ]
           }
         }
       }
     }
   ]
-}
+}