add relations to metadata element

docs/content/reference/mcf.md

@@ -141,6 +141,14 @@ Property Name|Mandatory/Optional|Description|Example|Reference
 identifier|Mandatory|identifier|10.5324/3f342f64|ISO 19115:2003 Section B.2.1
 scheme|Optional|scheme in which this identifier is defined (e.g. ark, doi, handle, isbn, lccn, sku).  Note that the schema may also be a URI|https://doi.org|ISO 19115:2003 Section B.2.1
 
+### `metadata.relations`
+
+Property Name|Mandatory/Optional|Description|Example|Reference
+-------------|------------------|-----------|-------|---------:
+identifier|Mandatory|identifier|10.5324/3f342f64|ISO 19115:2003 Section B.2.1
+scheme|Optional|scheme in which this identifier is defined (e.g. ark, doi, handle, isbn, lccn, sku).  Note that the schema may also be a URI|https://doi.org|ISO 19115:2003 Section B.2.1
+type|Optional|a relation type (source, partof, version, reference, ...)|source|ISO 19115:2003 Section B.2.1
+
 ### `spatial`
 
 Property Name|Mandatory/Optional|Description|Example|Reference

pygeometa/schemas/mcf/core.yaml

@@ -39,6 +39,17 @@ properties:
             parentidentifier:
                 type: string
                 description: file identifier of the metadata to which this metadata is a subset
+            relations:
+                type: array
+                description: relations to other records
+                items:
+                    type: object
+                    allOf:
+                        - $ref: '#/definitions/identifier_scheme'
+                    properties:
+                        type:
+                            type: string
+                            description: a relation type (source, partof, version, reference, ...)
             hierarchylevel:
                 type: string
                 description: level to which the metadata applies

sample.yml

@@ -10,6 +10,10 @@ metadata:
     language_alternate: fr
     charset: utf8
     parentidentifier: someparentid
+    relations:
+        - identifier: 10.278/45e22-11223-2
+          scheme: http://doi.org
+          type: source 
     hierarchylevel: dataset
     datestamp: 2014-11-11
     dataseturi: http://some/minted/uri