Remove media type registry mentions for encoding.

This removes the more general language allowing for future
expansion with the media type registry (although the general
language still had the same effect of restricting to `multipart`
and `application/x-www-form-urlencoded` in practice).

Author: handrews

src/oas.md

@@ -84,8 +84,6 @@ Some examples of possible media type definitions:
   application/vnd.github.v3.patch
 ```
 
-#### Media Type Registry
-
 ### HTTP Status Codes
 
 The HTTP Status Codes are used to indicate the status of the executed operation.
@@ -1617,33 +1615,33 @@ See [Working With Examples](#working-with-examples) for further guidance regardi
 | <a name="media-type-schema"></a>schema | [Schema Object](#schema-object) | The schema defining the content of the request, response, parameter, or header. |
 | <a name="media-type-example"></a>example | Any | Example of the media type; see [Working With Examples](#working-with-examples). |
 | <a name="media-type-examples"></a>examples | Map[ `string`, [Example Object](#example-object) \| [Reference Object](#reference-object)] | Examples of the media type; see [Working With Examples](#working-with-examples). |
-| <a name="media-type-encoding"></a>encoding | Map[`string`, [Encoding Object](#encoding-object)] | A map between a property name and its encoding information for media types supporting name-value pairs and allowing duplicate names, as defined under [Encoding Usage and Restrictions](#encoding-usage-and-restrictions). |
-
+| <a name="media-type-encoding"></a>encoding | Map[`string`, [Encoding Object](#encoding-object)] | A map between a property name and its encoding information, as defined under [Encoding Usage and Restrictions](#encoding-usage-and-restrictions).  The `encoding` field SHALL only apply when the media type is `multipart` or `application/x-www-form-urlencoded`. If no Encoding Object is provided for a property, the behavior is determined by the default values documented for the Encoding Object. |
 
 This object MAY be extended with [Specification Extensions](#specification-extensions).
 
 ##### Encoding Usage and Restrictions
 
+The `encoding` field defines how to map each [Encoding Object](#encoding-object) to a specific value in the data.
+
 To use the `encoding` field, a `schema` MUST exist, and the `encoding` field's  keys MUST exist in the schema as properties.
-Array properties MUST be handled by applying the given Encoding Object to multiple parts (or query parameters) with the same `name`, as is recommended by [RFC7578](https://www.rfc-editor.org/rfc/rfc7578.html#section-4.3) for supplying multiple values per form field.
-For all other property types, including array values within a top-level array, the Encoding Object MUST be applied to the entire value.
+Array properties MUST be handled by applying the given Encoding Object to one part per array item, each with the same `name`, as is recommended by [[?RFC7578]] [Section 4.3](https://www.rfc-editor.org/rfc/rfc7578.html#section-4.3) for supplying multiple values per form field.
+For all other value types for both top-level non-array properties and for values, including array values, within a top-level array, the Encoding Object MUST be applied to the entire value.
 
-The behavior of the `encoding` field is designed to support web forms, and is therefore only defined for media types structured as name-value pairs that allow repeat values.
+The behavior of the `encoding` field is designed to support web forms, and is therefore only defined for media types structured as name-value pairs that allow repeat values, most notably `application/x-www-form-urlencoded` and `multipart/form-data`.
 The order of these name-value pairs in the target media type is implementation-defined.
 
 For `application/x-www-form-urlencoded`, the encoding keys MUST map to parameter names, with the values produced according to the rules of the [Encoding Object](#encoding-object).
 See [Encoding the `x-www-form-urlencoded` Media Type](#encoding-the-x-www-form-urlencoded-media-type) for guidance and examples, both with and without the `encoding` field.
 
-For `multipart/*`, the encoding keys MUST map to the [`name` parameter](https://www.rfc-editor.org/rfc/rfc7578#section-4.2) of the `Content-Disposition: form-data` header of each part.
-See [RFC7578](https://www.rfc-editor.org/rfc/rfc7578.html#section-5) for guidance regarding non-ASCII part names.
+For `multipart`, the encoding keys MUST map to the [`name` parameter](https://www.rfc-editor.org/rfc/rfc7578#section-4.2) of the `Content-Disposition: form-data` header of each part, as is defined for `multipart/form-data` in [[?RFC7578]].
+See [[?RFC7578]] [Section 5](https://www.rfc-editor.org/rfc/rfc7578.html#section-5) for guidance regarding non-ASCII part names.
 
-This usage of a `name` [`Content-Disposition` parameter](https://www.iana.org/assignments/cont-disp/cont-disp.xhtml#cont-disp-2) is defined for `multipart/form-data` ([[?RFC7578]]) and the `form-data` [`Content-Disposition` value](https://www.iana.org/assignments/cont-disp/cont-disp.xhtml#cont-disp-1).
-Implementations MAY choose to support the `name` `Content-Disposition` parameter and the `encoding` field with other `multipart` formats, but this usage is unlikely to be supported by generic `multipart` implementations.
+Other `multipart` media types are not directly supported as they do not define a mechanism for part names.
+However, the usage of a `name` [`Content-Disposition` parameter](https://www.iana.org/assignments/cont-disp/cont-disp.xhtml#cont-disp-2) is defined for the `form-data` [`Content-Disposition` value](https://www.iana.org/assignments/cont-disp/cont-disp.xhtml#cont-disp-1), which is not restricted to `multipart/form-data`.
+Implementations MAY choose to support the a `Conent-Disposition` of `form-data` with a `name` parameter in other `multipart` media types in order to use the `encoding` field with them, but this usage is unlikely to be supported by generic `multipart` implementations.
 
 See [Encoding `multipart` Media Types](#encoding-multipart-media-types) for further guidance and examples, both with and without the `encoding` field.
 
-For all media types where no mapping is defined by either this specification or the [Media Type Registry](#media-type-registry), the `encoding` field SHALL be ignored.
-
 ##### Media Type Examples
 
 ```json