openapi: Clarified expectations for RFC 3339 on local times

- For temporal extent, allow local or UTC time
- For datetime parameter, server need to support at least UTC time
  (but may or may not support local time offsets)

collections/openapi/ogcapi-common-2.bundled.json

@@ -561,7 +561,7 @@
                 "type": "array",
                 "minItems": 1,
                 "items": {
-                  "description": "Begin and end times of the time interval. The timestamps are in the\ntemporal coordinate reference system specified in `trs`. By default\nthis is the Gregorian calendar.\n\nThe value `null` for start or end time is supported and indicates a half-bounded time interval.",
+                  "description": "Begin and end times of the time interval. The timestamps are in the\ntemporal coordinate reference system specified in `trs`. By default\nthis is the Gregorian calendar, expressed using RFC 3339 section 5.6.\nNote that these times may be specified using time zone offsets to UTC time other than zero.\n\nThe value `null` for start or end time is supported and indicates a half-bounded time interval.",
                   "type": "array",
                   "minItems": 2,
                   "maxItems": 2,
@@ -572,6 +572,7 @@
                   },
                   "example": [
                     "2011-11-11T12:22:11Z",
+                    "2011-11-11T08:22:11-04:00",
                     null
                   ]
                 }
@@ -683,6 +684,7 @@
                     },
                     "example": [
                       "2011-11-11T12:22:11Z",
+                      "2011-11-11T08:22:11-04:00",
                       32.5,
                       null
                     ]
@@ -883,7 +885,7 @@
       "datetime": {
         "name": "datetime",
         "in": "query",
-        "description": "Either a date-time or an interval. Date and time expressions adhere to RFC 3339. Intervals may be bounded or half-bounded (double-dots at start or end).\nExamples:\n* A date-time: \"2018-02-12T23:20:50Z\" * A bounded interval: \"2018-02-12T00:00:00Z/2018-03-18T12:31:12Z\" * Half-bounded intervals: \"2018-02-12T00:00:00Z/..\" or \"../2018-03-18T12:31:12Z\"\nOnly resources that have a temporal property that intersects the value of `datetime` are selected.\nIf a feature has multiple temporal properties, it is the decision of the server whether only a single temporal property is used to determine the extent or all relevant temporal properties.",
+        "description": "Either a date-time or an interval. Date and time expressions adhere to RFC 3339, section 5.6. Intervals may be bounded or half-bounded (double-dots at start or end). Server implementations may or may not support times expressed using time offsets from UTC, but need to support UTC time with the notation ending with a Z.\nExamples:\n* A date-time: \"2018-02-12T23:20:50Z\" * A bounded interval: \"2018-02-12T00:00:00Z/2018-03-18T12:31:12Z\" * Half-bounded intervals: \"2018-02-12T00:00:00Z/..\" or \"../2018-03-18T12:31:12Z\"\nOnly resources that have a temporal property that intersects the value of `datetime` are selected.\nIf a feature has multiple temporal properties, it is the decision of the server whether only a single temporal property is used to determine the extent or all relevant temporal properties.",
         "required": false,
         "schema": {
           "type": "string"

collections/openapi/parameters/common-geodata/datetime.yaml

@@ -2,7 +2,9 @@ name: datetime
 in: query
 description: >-
   Either a date-time or an interval. Date and time expressions
-  adhere to RFC 3339. Intervals may be bounded or half-bounded (double-dots at start or end).
+  adhere to RFC 3339, section 5.6. Intervals may be bounded or half-bounded (double-dots at start or end).
+  Server implementations may or may not support times expressed using time offsets from UTC, but need to support
+  UTC time with the notation ending with a Z.
 
   Examples:
 

collections/openapi/schemas/common-geodata/extent-uad.yaml

@@ -38,6 +38,7 @@ allOf:
                   - type: number
              example:
                - '2011-11-11T12:22:11Z'
+               - '2011-11-11T08:22:11-04:00'
                - 32.5
                - null
          trs:

collections/openapi/schemas/common-geodata/extent.yaml

@@ -176,7 +176,8 @@ properties:
           description: |-
             Begin and end times of the time interval. The timestamps are in the
             temporal coordinate reference system specified in `trs`. By default
-            this is the Gregorian calendar.
+            this is the Gregorian calendar, expressed using RFC 3339 section 5.6.
+            Note that these times may be specified using time zone offsets to UTC time other than zero.
 
             The value `null` for start or end time is supported and indicates a half-bounded time interval.
           type: array
@@ -188,6 +189,7 @@ properties:
             nullable: true
           example:
             - '2011-11-11T12:22:11Z'
+            - '2011-11-11T08:22:11-04:00'
             - null
       trs:
         description: |-

collections/requirements/searchable-collections/REQ_rc-datetime-definition.adoc

@@ -1,7 +1,7 @@
 [[req_collections_rc-datetime-definition]]
 [width="90%",cols="2,6a"]
 |===
-^|*Requirement {counter:req-id}* |*/req/collections/rc-datetime-definition* 
+^|*Requirement {counter:req-id}* |*/req/collections/rc-datetime-definition*
 ^|A |The `datetime` parameter SHALL have the following characteristics (using an OpenAPI Specification 3.0 fragment):
 
 [source,YAML]
@@ -25,6 +25,6 @@ interval-half-bounded-end   = date-time "/" [".."]
 interval                    = interval-bounded / interval-half-bounded-start / interval-half-bounded-end
 datetime                    = date-time / interval
 ----
-^|C |The syntax of `date-time` is specified by link:https://tools.ietf.org/html/rfc3339#section-5.6[RFC 3339, 5.6].
-^|D |Open ranges in time intervals at the start or end are supported using a double-dot (`..`) or an empty string for the start/end..
+^|C |Server implementations SHALL interpret the `date-time` as specified by link:https://tools.ietf.org/html/rfc3339#section-5.6[RFC 3339, 5.6] supporting at least UTC time with the notation ending with a Z (with support for local time offsets optional).
+^|D |When a double-dot (`..`) or an empty string is specified in a time interval, the implementation SHALL interpret it as a half-bounded or an unbounded interval (open range).
 |===