diff --git a/gtfs/spec/en/reference.md b/gtfs/spec/en/reference.md
index 055335586..c6953cab0 100644
--- a/gtfs/spec/en/reference.md
+++ b/gtfs/spec/en/reference.md
@@ -48,7 +48,7 @@ This section defines terms that are used throughout this document.
- **Date** - Service day in the YYYYMMDD format. Since time within a service day can be above 24:00:00, a service day often contains information for the subsequent day(s).
*Example: `20180913` for September 13th, 2018.*
- **Email** - An email address.
*Example: `example@example.com`*
- **Enum** - An option from a set of predefined constants defined in the "Description" column.
*Example: The `route_type` field contains a `0` for tram, a `1` for subway...*
-- **ID** - A sequence of any UTF-8 characters which uniquely identifies an entity, but does not necessarily identify a specific record in a table. IDs defined in one .txt file are often referenced in another .txt file. An ID field value is not aimed to be displayed to the user, and is a sequence of any UTF-8 characters, but using only printable ASCII characters is recommended.
*Example: The `stop_id` field in [stops.txt](#stopstxt) is a ID. The `stop_id` field in [stop_times.txt](#stop_timestxt) is an ID referencing `stops.stop_id`.*
+- **ID** - An ID field value is an internal ID, not intended to be shown to riders, and is a sequence of any UTF-8 characters. Using only printable ASCII characters is recommended. IDs defined in one .txt file are often referenced in another .txt file.
*Example: The `stop_id` field in [stops.txt](#stopstxt) is a ID. The `stop_id` field in [stop_times.txt](#stop_timestxt) is an ID referencing `stops.stop_id`.*
- **Language Code** - An IETF BCP 47 language code. For an introduction to IETF BCP 47, refer to [http://www.rfc-editor.org/rfc/bcp/bcp47.txt](http://www.rfc-editor.org/rfc/bcp/bcp47.txt) and [http://www.w3.org/International/articles/language-tags/](http://www.w3.org/International/articles/language-tags/).
*Example: `en` for English, `en-US` for American English or `de` for German.*
- **Latitude** - WGS84 latitude in decimal degrees. The value must be greater than or equal to -90.0 and less than or equal to 90.0. *
Example: `41.890169` for the Colosseum in Rome.*
- **Longitude** - WGS84 longitude in decimal degrees. The value must be greater than or equal to -180.0 and less than or equal to 180.0.
*Example: `12.492269` for the Colosseum in Rome.*
@@ -123,7 +123,7 @@ File: **Required**
| Field Name | Type | Required | Description |
| ------ | ------ | ------ | ------ |
-| `stop_id` | ID | **Required** | Identifies a stop, station, or station entrance. The term "station entrance" refers to both station entrances and station exits. Stops, stations or station entrances are collectively referred to as locations. Multiple routes may use the same stop. |
+| `stop_id` | ID | **Required** | Identifies a stop, station, or station entrance.
The term "station entrance" refers to both station entrances and station exits. Stops, stations or station entrances are collectively referred to as locations. Multiple routes may use the same stop. |
| `stop_code` | Text | Optional | Short text or a number that identifies the location for riders. These codes are often used in phone-based transit information systems or printed on signage to make it easier for riders to get information for a particular location. The `stop_code` can be the same as `stop_id` if it is public facing. This field should be left empty for locations without a code presented to riders. |
| `stop_name` | Text | **Conditionally Required** | Name of the location. Use a name that people will understand in the local and tourist vernacular.
When the location is a boarding area (`location_type=4`), the `stop_name` should contains the name of the boarding area as displayed by the agency. It could be just one letter (like on some European intercity railway stations), or text like “Wheelchair boarding area” (NYC’s Subway) or “Head of short trains” (Paris’ RER).
Conditionally Required:
• **Required** for locations which are stops (`location_type=0`), stations (`location_type=1`) or entrances/exits (`location_type=2`).
• Optional for locations which are generic nodes (`location_type=3`) or boarding areas (`location_type=4`).|
| `stop_desc` | Text | Optional | Description of the location that provides useful, quality information. Do not simply duplicate the name of the location. |