Merge pull request #19 from stac-api-extensions/pv/housekeeping

fix link to Part 3 and update software support for cql2

Author: Phil Varner

README.md

@@ -83,7 +83,7 @@
 The Filter extension provides an expressive mechanism for searching based on Item attributes.
 
 This extension references behavior defined in the
-[OGC API - Features - Part 3: Filtering and the Common Query Language (CQL2)](https://github.com/opengeospatial/ogcapi-features/tree/master/extensions/cql) and [Common Query Language (CQL2)
+[OGC API - Features - Part 3: Filtering and the Common Query Language (CQL2)](https://github.com/opengeospatial/ogcapi-features/tree/master/extensions/filtering) and [Common Query Language (CQL2)
 ](https://github.com/opengeospatial/ogcapi-features/blob/master/cql2/README.md)
 specifications. As of November 2021, these specifications are still in draft status, but rapidly converging on
 finalized behavior. Several behaviors have changed since the
@@ -234,20 +234,24 @@ implementing CQL2 Text. From there, other comparison operators can be implemente
 dynamic Queryables schema.
 
 Formal definitions and grammars for CQL2 can be found in the
-[OAFeat CQL spec](https://github.com/opengeospatial/ogcapi-features/tree/master/cql2) includes a BNF grammar
-  for CQL2 Text and both a JSON Schema and an OpenAPI specification for CQL2 JSON. The standalone files are:
-
+[OAFeat CQL spec](https://github.com/opengeospatial/ogcapi-features/tree/master/cql2) includes
+a BNF grammar for CQL2 Text and both a JSON Schema and an OpenAPI specification for CQL2 JSON.
+The standalone files are:
+  
 - [cql.bnf](https://github.com/opengeospatial/ogcapi-features/blob/master/extensions/cql/standard/schema/cql.bnf)
 - [cql.json](https://github.com/opengeospatial/ogcapi-features/blob/master/extensions/cql/standard/schema/cql.json)
 - [cql.yml](https://github.com/opengeospatial/ogcapi-features/blob/master/extensions/cql/standard/schema/cql.yml)
 
 These projects have or are developing CQL2 support:
 
-- [pgstac](https://github.com/stac-utils/pgstac) supports CQL2 JSON
-- [pygeofilter](https://github.com/geopython/pygeofilter) has support for CQL2 JSON and for the older ECQL standard that
+- [stac-fastapi-pgstac](https://github.com/stac-utils/stac-fastapi-pgstac) has support for
+  CQL2 Text and CQL2 JSON, via using [pygeofilter](https://github.com/geopython/pygeofilter)
+  to translate CQL2 Text to CQL2 JSON and processing the CQL2 JSON with
+  [pgstac](https://github.com/stac-utils/pgstac)
+- [pygeofilter](https://github.com/geopython/pygeofilter) handles both CQL2 Text and CQL2 JSON,
+  including the ability to convert from CQL2 Text to CQL2 JSON
 - [xtraplatform-spatial](https://github.com/interactive-instruments/xtraplatform-spatial) has support for CQL2 Text and provides an [ANTLR 4 grammer](https://github.com/interactive-instruments/xtraplatform-spatial/tree/master/xtraplatform-cql/src/main/antlr/de/ii/xtraplatform/cql/infra)
 - [Geotools](https://github.com/geotools/geotools) has support for [CQL2 text](https://github.com/geotools/geotools/tree/main/modules/library/cql/src/main/java/org/geotools/filter/text/cql2)
-- [Franklin](https://github.com/azavea/franklin) is working on it in [this PR](https://github.com/azavea/franklin/pull/750).
 
 Note that the [xbib CQL library (JVM)](https://github.com/xbib/cql) is the OASIS Contextual Query Language, not
 OGC CQL, and should not be used to implement this extension, as they are significantly different query languages.
@@ -256,9 +260,11 @@ not compliant with this extension.
 
 ## Queryables
 
-The Queryables mechanism allows a client to discover what terms are available for use when writing filter
-expressions. These terms are defined both over the entire catalog (at `/queryables`) and per collection (at `/collections/{collectionId}/queryables`). The decision as to which queryables to define
-for the entire catalog is at the discretion of the implementer, and can be anywhere between none and the union of all
+The Queryables mechanism allows a client to discover what terms are available for use when
+writing filter expressions. These terms are defined both over the entire catalog
+(at `/queryables`) and per collection (at `/collections/{collectionId}/queryables`).
+The decision as to which queryables to define for the entire catalog is at the discretion
+of the implementer, and can be anywhere between none and the union of all
 queryables across all collections.
 
 By default, the queryables are the only terms that may be used