Revert "Issue 555 refactor measures to use descriptors"

schemas/data/measure.description.md

@@ -1,3 +1,3 @@
 A measure is a concrete quantifiable data point of a particular metric.
 
-It has a value, and a unique identifier.
+It has a value, and optionally a unit, although the unit can be inferred from the measure's metric.

schemas/data/measure.example.1.json

@@ -1,3 +1,5 @@
 {
+  "@type": "https://ns.adobe.com/xdm/data/example-metric",
+  "xdm:unit": null,
   "xdm:value": 175
 }

schemas/data/measure.schema.json

@@ -14,6 +14,12 @@
   "definitions": {
     "measure": {
       "properties": {
+        "@type": {
+          "type": "string",
+          "format": "uri",
+          "description":
+            "Links to the `Metric` that this measure refers to. The `@type` can be omitted in contexts where it is obvious what metric is being referred to, for instance in the `Metrics` object that is keyed with `Metric` URIs."
+        },
         "xdm:id": {
           "title": "Unique Identifier",
           "type": "string",
@@ -23,6 +29,19 @@
         "xdm:value": {
           "type": "number",
           "description": "The quantifiable value of this measure."
+        },
+        "xdm:unit": {
+          "anyOf": [
+            {
+              "type": "string"
+            },
+            {
+              "const": null
+            }
+          ],
+          "description":
+            "The (optional) unit that this measure's value is measured in. The `unit` in the `Measure` is purely informational, as the `unit` property of the referenced `Metric` determines the interpretation.",
+          "examples": ["m", "kg", "s", "USD"]
         }
       }
     }