add details about link releation types

README.md

@@ -401,11 +401,16 @@ See the documentation for the
 ## Relation types
 
 The following types should be used as applicable `rel` types in the
-[Link Object](https://github.com/radiantearth/stac-spec/tree/master/item-spec/item-spec.md#link-object) of STAC Items describing Band Assets used with a model.
+[Link Object](https://github.com/radiantearth/stac-spec/tree/master/item-spec/item-spec.md#link-object)
+of STAC Items describing Band Assets that result from the inference of a model described by the MLM extension.
 
-| Type         | Description                                                                                                                                                            |
-|--------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| derived_from | This link points to <model>_item.json or <model>_collection.json.  Replace <model> with the unique [`mlm:name`](#item-properties-and-collection-fields) field's value. |
+| Type         | Description                                                                                                                                  |
+|--------------|----------------------------------------------------------------------------------------------------------------------------------------------|
+| derived_from | This link points to a STAC Collection or Item using MLM, using the corresponding [`mlm:name`](#item-properties-and-collection-fields) value. |
+
+Note that a derived product from model inference described by STAC should also consider using
+additional indications that it came of a model, such as described by
+the [Best Practices - Processing Extension](best-practices.md#processing-extension).
 
 ## Contributing
 

best-practices.md

@@ -63,6 +63,7 @@ A potential representation of a STAC Asset could be as follows:
 ```json
 {
   "model-output": {
+    "mlm:name": "<name-in-MLM-STAC-Item",
     "processing:level": "L4",
     "processing:expression": {
       "format": "stac-mlm",
@@ -72,6 +73,25 @@ A potential representation of a STAC Asset could be as follows:
 }
 ```
 
+Furthermore, the STAC Item representing the derived product could also include
+a [Link Object](https://github.com/radiantearth/stac-spec/tree/master/item-spec/item-spec.md#link-object)
+referring back to the MLM definition using `rel: derived_from`, as described in
+[MLM Relation Types](README.md#relation-types). Such a link would like something like the following:
+
+```json
+{
+  "links": [
+    {
+      "rel": "derived_from",
+      "type": "application/geo+json",
+      "href": "<URI-to-MLM-STAC-Item>",
+      "mlm:name": "<name-in-MLM-STAC-Item",
+      "processing:level": "L4"
+    }
+  ]
+}
+```
+
 ### ML-AOI and Label Extensions
 
 Supervised machine learning models will typically employ a dataset of training, validation and test samples.