Add q parameter #6, fix links #8, queryable clarifications #3, alignment #4

Author: m-mohr

README.md

@@ -12,7 +12,7 @@
   - [STAC API - Core](https://github.com/radiantearth/stac-api-spec/blob/main/core)
   - [STAC API - Collections](https://github.com/radiantearth/stac-api-spec/tree/main/ogcapi-features)
   - [OGC API - Common - Part 2: Geospatial Data](https://portal.ogc.org/files/99149)
-  - [OGC API - Records - Part 2: Collections](https://github.com/opengeospatial/ogcapi-records/tree/master/extensions/collections)
+  - [OGC API - Records - Part 1: Local Resource Catalogue](https://docs.ogc.org/DRAFTS/20-004.html#clause-local-resources-catalogue)
 - **Owner**: @m-mohr
 
 A search endpoint provides the ability to query
@@ -25,11 +25,11 @@ The Collection Search endpoint by default doesn't provide any query parameters t
 additional behavior will be defined in [Extensions](#extensions). These extensions can be composed
 by an implementer to cover only the set of functionality the implementer requires.
 
-This extension is based on *[OGC API - Common - Part 2: Geospatial Data](https://portal.ogc.org/files/99149#rc-simple-query-section)* and *[OGC API - Records - Part 2: Collections](https://github.com/opengeospatial/ogcapi-records/tree/master/extensions/collections)*
+This extension is based on *[OGC API - Common - Part 2: Geospatial Data](https://portal.ogc.org/files/99149#rc-simple-query-section)*
+and aligned to *[OGC API - Records - Part 1: Local Resource Catalogue](https://docs.ogc.org/DRAFTS/20-004.html#clause-local-resources-catalogue)*
 and selectively implements a subset of their "requirements classes".
 
-All functionality is only defined for `GET /collections` in *OGC API - Records - Part 2: Collections*.
-
+All functionality in *OGC API - Records - Part 1: Local Resource Catalogue* is only defined for the `GET` method (i.e. `GET /collections`).
 *Note:* STAC may add behavior for `POST /collections` in the future, but due to a potential conflict
 with the Transaction Extension, specific rules for content negotiation might be required.
 
@@ -44,29 +44,41 @@ for details.
 ### Basics
 
 A basic set of query parameters MUST be implemented.
-These are aligned with the corresponding parameters in STAC API - Features:
-- `bbox`
-- `datetime`
-- `limit`
+These are aligned with the corresponding parameters in STAC API - Features and OGC API - Records:
+- [`bbox`](https://docs.ogc.org/DRAFTS/20-004.html#_parameter_bbox) (intersection of the given `bbox` with any of the spatial extent provided in a STAC Collection at `extent.spatial.bbox`)
+- [`datetime`](https://docs.ogc.org/DRAFTS/20-004.html#_parameter_datetime) (intersection of the given `datetime` with any of the temporal extent provided in a STAC Collection at `extent.temporal.interval`)
+- [`limit`](https://docs.ogc.org/DRAFTS/20-004.html#_parameter_limit)
 
 Requirement class in *OGC API - Common - Part 2: Geospatial Data*: [Simple Query](https://portal.ogc.org/files/99149#rc-simple-query-section)
 
 ### Extensions
 
+#### Free text search
+
+A free-text search parameter `q` based on OGC API - Records can be added.
+See <https://docs.ogc.org/DRAFTS/20-004.html#_parameter_q> for details.
+It is case-insensitive and matches the string given strictly.
+The specific set of text keys/fields/properties of a Collection to which the parameter is applied is left to the discretion of the implementation, but a recommendation is to at least consider `title`, `description` and `keywords`.
+
+- Requirement class in *OGC API - Records*: n/a
+- Conformance class: `https://api.stacspec.org/v1.0.0-rc.1/collection-search#free-text`
+
 #### Query (STACQL)
 
 The query extension for STACQL support can be implemented, too. It works as it does for Items.
 See <https://github.com/stac-api-extensions/query> for details.
 
-- Requirement class in *OGC API - Records - Part 2: Collections*: n/a
+- Requirement class in *OGC API - Records*: n/a
 - Conformance class: `https://api.stacspec.org/v1.0.0-rc.1/collection-search#query`
 
 #### Filter (CQL)
 
-The filter extension for CQL support can be implemented, too. It works as it does for Items.
+The filter extension for CQL support can be implemented, too.
 See <https://github.com/stac-api-extensions/filter> for details.
+It works as it does for Items, except that the queryables link for Collection Search is located in the response of `GET /collections` (property `links`).
+The path/endpoint for Collection Search queryables can be freely chosen, but SHOULD NOT conflict with `GET /queryables`.
 
-- Requirement class in *OGC API - Records - Part 2: Collections*: CQL Filter
+- Requirement class in *OGC API - Records*: CQL Filter
 - Conformance classes:
   - `https://api.stacspec.org/v1.0.0-rc.1/collection-search#filter`
   - `http://www.opengis.net/spec/ogcapi-records-1/1.0/req/cql-filter`
@@ -76,7 +88,7 @@ See <https://github.com/stac-api-extensions/filter> for details.
 The sort extension can be implemented, too. It works as it does for Items.
 See <https://github.com/stac-api-extensions/sort> for details.
 
-- Requirement class in *OGC API - Records - Part 2: Collections*: Sorting
+- Requirement class in *OGC API - Records*: Sorting
 - Conformance classes:
   - `https://api.stacspec.org/v1.0.0-rc.1/collection-search#sort`
   - `http://www.opengis.net/spec/ogcapi-records-1/1.0/req/sorting`
@@ -86,13 +98,5 @@ See <https://github.com/stac-api-extensions/sort> for details.
 The fields extension can be implemented, too. It works as it does for Items.
 See <https://github.com/stac-api-extensions/fields> for details.
 
-- Requirement class in *OGC API - Records - Part 2: Collections*: n/a
+- Requirement class in *OGC API - Records*: n/a
 - Conformance class: `https://api.stacspec.org/v1.0.0-rc.1/collection-search#fields`
-
-#### Context
-
-The context extension can be implemented, too. It works as it does for Items.
-See <https://github.com/stac-api-extensions/context> for details.
-
-- Requirement class in *OGC API - Records - Part 2: Collections*: n/a
-- Conformance class: `https://api.stacspec.org/v1.0.0-rc.1/collection-search#context`