Merge pull request #1099 from radiantearth/utc

All timestamps in UTC

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - 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))
 - Updated examples for automatic collection creation from code and validation ([#1080](https://github.com/radiantearth/stac-spec/pull/1080)
 - Clarified that stac_extensions should also list extensions that are used in Collection summaries. ([#1077](https://github.com/radiantearth/stac-spec/issues/1077))
+- `changed`, `created` (common metadata) and temporal extents (collections): Timestamps must be always in UTC ([#1095](https://github.com/radiantearth/stac-spec/issues/1095))
 
 ## [v1.0.0-rc.2] - 2021-03-30
 

collection-spec/collection-spec.md

@@ -197,7 +197,7 @@ Clients only interested in the overall extent will only need to access the first
 It is recommended to only use multiple temporal extents if a union of them would then include a large
 uncovered time span (e.g. only having data for the years 2000, 2010 and 2020).
 
-Each inner array consists of exactly two dates and times.
+Each inner array consists of exactly two dates and times, each in UTC.
 Each date and time MUST be formatted according to [RFC 3339, section 5.6](https://tools.ietf.org/html/rfc3339#section-5.6).
 The temporal reference system is the Gregorian calendar.
 

collection-spec/json-schema/collection.json

@@ -153,7 +153,8 @@
                         "string",
                         "null"
                       ],
-                      "format": "date-time"
+                      "format": "date-time",
+                      "pattern": "(\\+00:00|Z)$"
                     }
                   }
                 }

item-spec/common-metadata.md

@@ -43,8 +43,8 @@ Fields to provide additional temporal information such as ranges with a start an
 | Field Name | Type         | Description |
 | ---------- | ------------ | ----------- |
 | datetime   | string\|null | See the [Item Spec Fields](item-spec.md#properties-object) for more information. |
-| created    | string       | Creation date and time of the corresponding data (see below). |
-| updated    | string       | Date and time the corresponding data (see below) was updated last. |
+| created    | string       | Creation date and time of the corresponding data (see below), in UTC. |
+| updated    | string       | Date and time the corresponding data (see below) was updated last, in UTC. |
 
 All timestamps MUST be formatted according to [RFC 3339, section 5.6](https://tools.ietf.org/html/rfc3339#section-5.6).
 

item-spec/item-spec.md

@@ -127,7 +127,7 @@ resources below.
 
 | Field Name | Type         | Description                                                  |
 | ---------- | ------------ | ------------------------------------------------------------ |
-| datetime   | string\|null | **REQUIRED.** The searchable date and time of the assets, in UTC. It is formatted according to [RFC 3339, section 5.6](https://tools.ietf.org/html/rfc3339#section-5.6). `null` is allowed, but requires `start_datetime` and `end_datetime` from [common metadata](common-metadata.md#date-and-time-range) to be set. |
+| datetime   | string\|null | **REQUIRED.** The searchable date and time of the assets, which must be in UTC. It is formatted according to [RFC 3339, section 5.6](https://tools.ietf.org/html/rfc3339#section-5.6). `null` is allowed, but requires `start_datetime` and `end_datetime` from [common metadata](common-metadata.md#date-and-time-range) to be set. |
 
 #### datetime
 
@@ -136,7 +136,8 @@ or representative time in the case of assets that are combined together. Though
 complex thing to capture, for this purpose keep in mind the STAC spec is primarily searching for
 data, so use whatever single date and time is most useful for a user to search for. STAC content
 extensions may further specify the meaning of the main `datetime` field, and many will also add more
-datetime fields.
+datetime fields. **All times in STAC metadata should be in [Coordinated Universal 
+Time](https://en.wikipedia.org/wiki/Coordinated_Universal_Time) (UTC).**
 If there's clearly no meaningful single 'nominal' time, it is allowed to use `null` instead.
 In this case it is **required** to specify a temporal interval with the fields `start_datetime`
 and `end_datetime` from [common metadata](common-metadata.md#date-and-time-range). For example, if

item-spec/json-schema/datetime.json

@@ -20,29 +20,34 @@
       "title": "Date and Time",
       "description": "The searchable date/time of the assets, in UTC (Formatted in RFC 3339) ",
       "type": ["string", "null"],
-      "format": "date-time"
+      "format": "date-time",
+      "pattern": "(\\+00:00|Z)$"
     },
     "start_datetime": {
       "title": "Start Date and Time",
       "description": "The searchable start date/time of the assets, in UTC (Formatted in RFC 3339) ",
       "type": "string",
-      "format": "date-time"
+      "format": "date-time",
+      "pattern": "(\\+00:00|Z)$"
     }, 
     "end_datetime": {
       "title": "End Date and Time", 
       "description": "The searchable end date/time of the assets, in UTC (Formatted in RFC 3339) ",                  
       "type": "string",
-      "format": "date-time"
+      "format": "date-time",
+      "pattern": "(\\+00:00|Z)$"
     },
     "created": {
       "title": "Creation Time",
       "type": "string",
-      "format": "date-time"
+      "format": "date-time",
+      "pattern": "(\\+00:00|Z)$"
     },
     "updated": {
       "title": "Last Update Time",
       "type": "string",
-      "format": "date-time"
+      "format": "date-time",
+      "pattern": "(\\+00:00|Z)$"
     }
   }
 }