Revert "revisioning of areas in stop_times"

spec/reference.md

@@ -44,16 +44,15 @@ Specifically, we propose the following additions to **stop_times.txt**:
 
 | Field Name | Required?  | Details |
 |------------|------------|---------|
-| pickup\__area\_id | Optional | The **pickup\__area\_id** specifies the id of a service area defined in the areas.txt file. When specified for a stop-time entry, it indicates that the transit vehicle may potentially pick-up passengers anywhere in the specified service area until the subsequent stop-time entry, according to the parameters provided within the **drt\_pickup\_message** field. | 
-| drop\_off\_area\_id | Optional | The **drop\_off\_area\_id** specifies the id of a service area defined in the areas.txt file. When specified for a stop-time entry, it indicates that the transit vehicle may potentially drop off passengers anywhere in the specified service area until the subsequent stop-time entry, according to the parameters provided within the **drt\_drop\_off\_message** field. |
-| pickup\_area\_radius | Optional | The **pickup\_area\_radius** field provides a convenient way to construct a service area without the need to define an area in **areas.txt**.  When specified, it indicates a distance in meters from the main path of travel for the trip where service is offered. The trip must specify a **shape\_id** if **pickup\_area\_radius** is specified. The **pickup\_area\_radius** field has the same semantics as **pickp\_area\_id** in terms of pick up semantics. |
-| drop\_off\_area\_radius | Optional | The **drop\_off\_area\_radius** field provides a convenient way to construct a service area without the need to define an area in **areas.txt**.  When specified, it indicates a distance in meters from the main path of travel for the trip where service is offered. The trip must specify a **shape\_id** if **drop\_off\_area\_radius** is specified. The **drop\_off\_area\_radius** field has the same semantics as **drop\_off\_area\_id** in terms of drop off semantics. |
+| start\_service\_area\_id | Optional | The **start\_service\_area\_id** specifies the id of a service area defined in the areas.txt file. When specified for a stop-time entry, it indicates the beginning of service in the specified service area and that the transit vehicle may potentially pick-up or drop-off passenger anywhere in the specified service area, as controlled by the **pickup\_type** and **drop\_off\_type** fields. Must be followed by a corresponding stop-time entry in the trip with a matching **end\_service\_area\_id** value. | 
+| end\_service\_area\_id | Optional | The **end\_service\_area\_id** specifies the id of a service area defined in the **areas.txt** file. When specified for a stop-time entry, it indicates the end of service in the specified service area. Must be preceded by a corresponding stop-time entry in the trip with a matching **start\_service\_area\_id** value. The **pickup\_type** and **drop\_off\_type** fields will be ignored for this stop-time entry. |
+| start\_service\_area\_radius | Optional | The **start\_service\_area\_radius** field provides a convenient way to construct a service area without the need to define an area in **areas.txt**.  When specified, it indicates a distance in meters from the main path of travel for the trip where service is offered. The trip must specify a **shape\_id** if **start\_service\_area\_radius** is specified. The **start\_service\_area\_radius** field has the same semantics as **start\_service\_area\_id** in terms of pickup/dropoff semantics. |
+| end\_service\_area\_radius | Optional | The **end\_service\_area\_radius** specifies the end of an area started by a stop-time entry with a **start\_service\_area\_radius** field. Must be preceded by a corresponding stop-time entry in the trip with the same **start\_service\_area\_radius** value. The **pickup\_type** and **drop\_off\_type** fields will be ignored for this stop-time entry. |
 
 Regarding **stop\_id**, two possibilities:
 
 * We allow **stop\_id** to be empty when **start\_service\_area\_id** has been specified. This breaks the idea that **stop\_id** is always required, but is conceptually cleaner.
 * We still require **stop\_id** to be specified. It should specify a stop at the center of the service area and might be used to provide additional data for the service area (name? url? fare zone?).
-* Following the revision of area-related fields in **stop\_times.txt**, the **stop\_id** field would be best used to indicate the origin point of the vehicle at the initiation of the pickup or drop off service. In the case of a deviated-fixed service, this will naturally be the previous fixed-route stop. In a general dial-a-ride scenario, this would likely be the depot point where the vehicle begins service.
 
 Regarding **arrival\_time** and **departure\_time**, these fields can be used to specify rough timing information for a route deviation or flexible route segment relative to other parts of the route, or can be left blank if it’s not the first or last stop-time in the trip. If a time is specified, it indicates when service begins in the area.