First implementation (#1)

Reviewed-on: #1

schemas/value-anchor.schema.json

@@ -0,0 +1,53 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://paperspec.scient.ing/schemas/value-anchor.schema.json",
+  "title": "Value anchor",
+  "description": "One line of a dataset's anchors.jsonl: where one value came from; spec/15-datasets.md.",
+  "type": "object",
+  "properties": {
+    "resource": {
+      "$ref": "common.schema.json#/$defs/key"
+    },
+    "row": {
+      "$ref": "common.schema.json#/$defs/key"
+    },
+    "field": {
+      "type": "string",
+      "minLength": 1
+    },
+    "anchor": {
+      "$ref": "anchor.schema.json"
+    },
+    "digitization": {
+      "$ref": "common.schema.json#/$defs/recordId"
+    },
+    "series": {
+      "type": "string",
+      "minLength": 1
+    },
+    "point": {
+      "type": "integer",
+      "minimum": 0
+    }
+  },
+  "required": [
+    "resource",
+    "row",
+    "field"
+  ],
+  "additionalProperties": false,
+  "oneOf": [
+    {
+      "required": [
+        "anchor"
+      ]
+    },
+    {
+      "required": [
+        "digitization",
+        "series",
+        "point"
+      ]
+    }
+  ]
+}