add single file STAC extension

CHANGELOG.md

@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - **stac_extensions**: Introduced this field for Items, Catalogs and Collections.
 - Property `summaries` have been added to catalogs and collections.
 - API Transaction extension supports optimistic locking through use of the ETag header.
+- [Single File Catalog extension](extensions/single-file-catalog/README.md) added as a format to have a set of Collections and Items in a single file.
 - [Label extension](extensions/label/README.md) added with additional fields for describing labeled data, such as used for training data or from the output of a classification
 - Timestamp fields added to `Item`: `created` and `updated` to refer to the datetime the metadata file was created or updated.
 - Added Search Metadata API extension which adds fields to a response from a STAC API such as the number of items found and how many were returned.

extensions/README.md

@@ -54,7 +54,12 @@ An extension can add new fields to STAC entities (content extension), or can add
 | [Label](label/README.md) (`label`)                           | Item             | Items that relate labeled AOIs with source imagery | *Proposal* |
 | [Point Cloud](pointcloud/README.md) (`pc`)                   | Item             | Provides a way to describe point cloud datasets. The point clouds can come from either active or passive sensors, and data is frequently acquired using tools such as LiDAR or coincidence-matched imagery. | *Proposal* |
 | [SAR](sar/README.md) (`sar`)                                 | Item             | Covers synthetic-aperture radar data that represents a snapshot of the earth for a single date and time. | *Proposal* |
+<<<<<<< HEAD
+| [Scientific](scientific/README.md) (`sci`)                   | Item             | Scientific metadata is considered to be data that indicate from which publication data originates and how the data itself should be cited or referenced. | *Proposal* |
+| [Single File STAC](single-file-stac/README.md) (-)                   | Catloag +Collection +Item | An extension to provide a set of Collections and Items as a single file catalog. | *Proposal* |
+=======
 | [Scientific](scientific/README.md) (`sci`)                   | Item +Collection | Scientific metadata is considered to be data that indicate from which publication data originates and how the data itself should be cited or referenced. | *Proposal* |
+>>>>>>> a76d904270c4a369582b2319daa655e97d3f1b02
 
 ## Third-party / vendor extensions
 

extensions/single-file-stac/README.md

@@ -0,0 +1,30 @@
+# Single File STAC Specification
+
+**Extension [Maturity Classification](../README.md#extension-maturity): Proposal**
+
+An extension to provide a set of Collections and Items as a single file catalog.
+
+- [Example](examples/example.json)
+- [JSON Schema](json-schema/schema.json)
+
+## Catalog fields
+
+A Single File STAC is a complete STAC catalog contained in a single file. It is sometimes useful to save a portion of a catalog (such as gained through a search) as single file so it is more portable than a set of linked files.
+
+A Single File STAC is an [ItemCollection Object](../../item-spec/itemcollection-spec.md). This GeoJSON FeatureCollection has Features which are Items, but the Collections are still needed.
+
+| Field Name         | Type   | Description                                                  |
+| ------------------ | ------ | ------------------------------------------------------------ |
+| collections | [Collection](../../collection-spec/collection-spec.md#collection-fields)] | An array of Collections that are used by any of the Items in the ItemCollection.
+| search | [Search Object](#search-object) | An optional field containing a search endpoint and parameters used to generate this Single File STAC |
+
+## Search Object
+
+| Field Name         | Type   | Description                                                  |
+| ------------------ | ------ | ------------------------------------------------------------ |
+| endpoint | string | The root endpoint of a STAC API used for this search.
+| parameters | map<string, Object> | A dictionary of all the parameters used for the search |
+
+## Implementations
+
+- [sat-search](https://github.com/sat-utils/sat-search) uses the Single File Catalog to save and load search results.