include parent and root rel types, even for same file

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Added
 
 - Added `preview` relation type for interoperable thumbnails to best practices. ([#1090](https://github.com/radiantearth/stac-spec/issues/1090))
+- Recommendation to include both `root` and `parent` relation types when they point at the same file.
 
 ### Changed
 

best-practices.md

@@ -641,6 +641,10 @@ a number of the common official relations that are used in production STAC imple
 | next      | Indicates that the link's context is a part of a series, and that the next in the series is the link target. Typically used in STAC by API's, to return smaller groups of Items or Catalogs/Collections. |
 | preview   | Refers to a resource that serves as a preview (see [RFC 6903, sec. 3](https://tools.ietf.org/html/rfc6903#section-3)), usually a lower resolution thumbnail. In STAC this would usually be the same URL as the [thumbnail](#thumbnail) asset, but adding it as a link in addition enables OGC API clients that can't read assets to make use of it. It also adds support for thumbnails to STAC Catalogs as they can't list assets. |
 
+Being liberal with the `links` also means that it's ok to have repeated links with the same `rel`. For example the
+`parent` and `root` relation types will point at the same file when the child is directly below the root, and it is
+recommended to include both.
+
 ### Versioning for Catalogs
 
 In the Item and Collection STAC JSON, versions and deprecation can be indicated with the

examples/core-item.json

@@ -65,6 +65,11 @@
       "href": "./collection.json",
       "type": "application/json"
     },
+    {
+      "rel": "parent",
+      "href": "./collection.json",
+      "type": "application/json"
+    },
     {
       "rel": "alternate",
       "type": "text/html",

examples/extended-item.json

@@ -93,6 +93,11 @@
       "href": "./collection.json",
       "type": "application/json"
     },
+    {
+      "rel": "parent",
+      "href": "./collection.json",
+      "type": "application/json"
+    },
     {
       "rel": "alternate",
       "type": "text/html",

examples/simple-item.json

@@ -51,6 +51,11 @@
       "rel": "root",
       "href": "./collection.json",
       "type": "application/json"
+    },
+    {
+      "rel": "parent",
+      "href": "./collection.json",
+      "type": "application/json"
     }
   ],
   "assets": {