add extensions section to ocgapi-features, cleanup other extensions s…

core/README.md

@@ -3,6 +3,7 @@
 - [STAC API - Core Specification](#stac-api---core-specification)
   - [Recommended Link Relations at `/`](#recommended-link-relations-at-)
   - [Example Landing Page for STAC API - Core](#example-landing-page-for-stac-api---core)
+  - [Extensions](#extensions)
 
 - **OpenAPI specification:** [openapi.yaml](openapi.yaml) describes the core endpoints ([rendered version](https://api.stacspec.org/v1.0.0-beta.2/core)),
   and [commons.yaml](commons.yaml) is the OpenAPI version of the core [STAC spec](../stac-spec) JSON Schemas.
@@ -111,3 +112,7 @@ the [overview](../overview.md#example-landing-page) document.
     ]
 }
 ```
+
+## Extensions
+
+None.

item-search/README.md

@@ -60,9 +60,10 @@ Implementations that support `POST` must add a second link with the same structu
 
 ## Query Parameters and Fields
 
-The following list of parameters is used to narrow search queries. They can all be represented as query string parameters 
-in a GET request, or as JSON entity fields in a POST request. For filters that represent a set of values, query parameters 
-should use comma-separated string values with no enclosing brackets (\[ or \]) and no whitespace between values, and JSON entity attributes should use JSON Arrays. 
+The following list of parameters is used to narrow search queries. They can all be represented as query 
+string parameters in a GET request, or as JSON entity fields in a POST request. For filters that represent 
+a set of values, query parameters should use comma-separated string values with no enclosing brackets 
+(\[ or \]) and no whitespace between values, and JSON entity attributes should use JSON Arrays. 
 
 ### Query Examples
 
@@ -99,7 +100,6 @@ should be returned. See [examples](examples.md) to see sample requests.
 
 **bbox** Represented using either 2D or 3D geometries. The length of the array must be 2\*n where n is the number of dimensions. The array contains all axes of the southwesterly most extent followed by all axes of the northeasterly most extent specified in Longitude/Latitude or Longitude/Latitude/Elevation based on [WGS 84](http://www.opengis.net/def/crs/OGC/1.3/CRS84). When using 3D geometries, the elevation of the southwesterly most extent is the minimum elevation in meters and the elevation of the northeasterly most extent is the maximum.  
 
-
 ## Response
 
 The response to a request (GET or POST) to the search endpoint should always be an 
@@ -258,7 +258,7 @@ the [overview](../overview.md#example-landing-page) document.
 
 ## Extensions
 
-These extensions provide additional functionality that enhances the core item search. All are specified as 
+These extensions provide additional functionality that enhances Item Search. All are specified as 
 [fragments](../fragments), as they are re-used by other extensions STAC API's that offer the following capabilities at
 the `search` endpoint must include the relevant **conformance URI** in the `conformsTo` response at
 the root (`/`) landing page, to indicate to clients that they will respond properly to requests from clients.

ogcapi-features/README.md

@@ -4,6 +4,9 @@
   - [Endpoints](#endpoints)
   - [Examples](#examples)
   - [Example Landing Page for STAC API - Features](#example-landing-page-for-stac-api---features)
+  - [Extensions](#extensions)
+    - [Transaction](#transaction)
+    - [Items and Collections API Version Extension](#items-and-collections-api-version-extension)
 
 *based on [**OGC API - Features - Part 1: Core**](https://www.ogc.org/standards/ogcapi-features)*
 
@@ -159,3 +162,34 @@ the [overview](../overview.md#example-landing-page) document.
     ]
 }
 ```
+
+## Extensions
+
+These extensions provide additional functionality that enhances STAC API - Features. 
+All are specified as [fragments](../fragments), as they are re-used by extensions to other STAC APIs.
+STAC APIs that offer the following capabilities must include the relevant **conformance URI** in the 
+`conformsTo` response at the root (`/`) landing page, to indicate to clients that they will respond properly 
+to requests from clients.
+
+### Transaction
+
+- **Conformance URIs:**
+  - <https://api.stacspec.org/v1.0.0-beta.2/ogcapi-features/extensions/transaction>
+  - <http://www.opengis.net/spec/ogcapi-features-4/1.0/conf/simpletx>
+- **Extension [Maturity Classification](../extensions.md#extension-maturity):** Pilot
+- **Definition**: [STAC API - Transaction Fragment](extensions/transaction/)
+
+The core STAC API only supports retrieving existing Items.
+The Transaction extension supports the creation, editing, and deleting of items through the use of the 
+POST, PUT, PATCH, and DELETE methods. The full description of how this extension works can be found in the 
+[transaction fragment](extensions/transaction/). 
+
+### Items and Collections API Version Extension
+
+- **Conformance URI:** <https://api.stacspec.org/v1.0.0-beta.2/ogcapi-features/extensions/version>
+- **Extension [Maturity Classification](../extensions.md#extension-maturity):** Pilot
+- **Definition**: [STAC API - Version](extensions/version/)
+
+The core API only supports semantics for creating and accessing a single version of an Item or Collection.
+The Version Extension defines the API resources and semantics for creating and accessing versioned records.
+It is the STAC API equivalent of [OGC API - Features - Part 4: Create, Replace, Update and Delete](https://docs.ogc.org/DRAFTS/20-002.html).

ogcapi-features/extensions/version/README.md

@@ -7,8 +7,7 @@
 
 The core API doesn't support semantics to creating and accessing different versions of an Item or Collection.
 This version API extension defines the API resources and semantics for creating and accessing versioned records.
-It is done on the OGC API - Features endpoints, and ideally should evolve to be an extension there, but it is
-incubated in STAC.
+It is the STAC API equivalent of [OGC API - Features - Part 4: Create, Replace, Update and Delete](https://docs.ogc.org/DRAFTS/20-002.html).
 
 ## Methods