Clarified parking category definitions

Author: schnuerle

data-types.md

@@ -219,7 +219,7 @@ A Trip is defined by the following structure:
 | `publication_time`       | [Timestamp][ts] | Optional | Date/time that trip became available through the trips endpoint |
 | `accessibility_options`  | Enum[]          | Required | **[Mode](/modes#list-of-supported-modes) Specific**. [Accessibility options](/modes#accessibility-options) given as an array of enumerated values. List of any accessibility options **used during the trip**. |
 | `parking_verification_url` | URL           | Optional | A URL to a photo (or other evidence) of proper vehicle parking at the end of a trip, provided by customer or operator. |
-| `parking_category`       | Enum            | Optional | The type of parking location detected or provided and the end of a trip. One of `corral`, `curb`, `rack`, `invalid`, `other`. 
+| `parking_category`       | Enum            | Optional | The type of parking location detected or provided and the end of a trip. One of `corral`, `curb`, `rack`, `other_valid`, `invalid`. Note that `other_valid` covers any other allowed parking location beyond what is enumerated, and `invalid` is any improper parking based on agency parking rules.
 | `standard_cost`          | Integer         | Optional | The cost, in the currency defined in `currency`, to perform that trip in the standard operation of the System (see [Costs & Currencies][costs-and-currencies]) |
 | `actual_cost`            | Integer         | Optional | The actual cost, in the currency defined in `currency`, paid by the customer of the *mobility as a service* provider (see [Costs & Currencies][costs-and-currencies]) |
 | `currency`               | String          | Optional, USD cents is implied if null.| An [ISO 4217 Alphabetic Currency Code][iso4217] representing the currency of the payee (see [Costs & Currencies][costs-and-currencies]) |