Merge pull request #1078 from radiantearth/rephrase-stac-extensions

Clarified stac_extensions

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [Unreleased]
 
 ### Changed
+
+- Clarified that stac_extensions should also list extensions that are used in Collection summaries. ([#1077](https://github.com/radiantearth/stac-spec/issues/1077))
 - The first extent in a Collection is always the overall extent, followed by more specific extents. ([#1064](https://github.com/radiantearth/stac-spec/issues/1064), [opengeospatial/ogcapi-features#520](https://github.com/opengeospatial/ogcapi-features/pull/520))
 
 ## [v1.0.0-rc.2] - 2021-03-30

catalog-spec/catalog-spec.md

@@ -61,9 +61,10 @@ In general, STAC versions can be mixed, but please keep the [recommended best pr
 #### stac_extensions
 
 A list of extensions the Catalog implements.
-This list must only contain extensions that extend the Catalog itself, see the the 'Scope' column in the list of
-extensions. This does NOT declare the extensions of child Catalog, Collection, or Item
-objects. The list contains URLs to the JSON Schema files it can be validated against.
+The list consists of URLs to JSON Schema files that can be used for validation.
+This list must only contain extensions that extend the Catalog specification itself,
+see the 'Scope' for each of the extensions.
+This must **not** declare the extensions that are only implemented in child Collection objects or child Item objects.
 
 ### Link Object
 

collection-spec/collection-spec.md

@@ -65,16 +65,11 @@ In general, STAC versions can be mixed, but please keep the [recommended best pr
 
 #### stac_extensions
 
-A list of extensions the Collection implements.  
-This list must only contain extensions that extend the Collection itself, see the the 'Scope' column in the list of 
-extensions. This does NOT declare the extensions of child Collection or Item 
-objects. The list contains URLs to the JSON Schema files it can be validated against.
-
-If an extension has influence on multiple parts 
-of the whole STAC structure, it must be listed in all affected parts (e.g. Collection and Item for the `datacube` extension). 
-If a structure, such as the summaries extension, provides fields in their JSON structure, these extensions must not be listed 
-here as they don't extend the Collection itself. For example, if a Collection includes the field `sat:platform` in the 
-summaries, the Collection should not list the `sat` extension in the `stac_extensions` field.
+A list of extensions the Collection implements.
+The list consists of URLs to JSON Schema files that can be used for validation.
+This list must only contain extensions that extend the Collection specification itself,
+see the the 'Scope' for each of the extensions.
+This must **not** declare the extensions that are only implemented in child Collection objects or child Item objects.
 
 #### id
 

item-spec/item-spec.md

@@ -73,11 +73,10 @@ In general, STAC versions can be mixed, but please keep the [recommended best pr
 
 #### stac_extensions
 
-A list of extensions the Item implements.  
-This list must only contain extensions that extend the Item itself, see the the 'Scope' column in the list of 
-extensions. The list contains URLs to the JSON Schema files it can be validated against.
-If an extension such as the `tiled-assets` extension has influence on multiple parts of the whole catalog 
-structure, it must be listed in all affected parts (e.g. Catalog, Collection and Item for the `tiled-assets` extension).
+A list of extensions the Item implements.
+The list consists of URLs to JSON Schema files that can be used for validation.
+This list must only contain extensions that extend the Item specification itself,
+see the the 'Scope' for each of the extensions.
 
 #### id