OAI · handrews · Aug 2, 2025
@@ -1152,7 +1152,7 @@ Serializing with `schema` is NOT RECOMMENDED for `in: "cookie"` parameters, `in:
 | Field Name | Type | Description |
 | ---- | :----: | ---- |
 | <a name="parameter-style"></a>style | `string` | Describes how the parameter value will be serialized depending on the type of the parameter value. Default values (based on value of `in`): for `"query"` - `"form"`; for `"path"` - `"simple"`; for `"header"` - `"simple"`; for `"cookie"` - `"form"`. |
-| <a name="parameter-explode"></a>explode | `boolean` | When this is true, parameter values of type `array` or `object` generate separate parameters for each value of the array or key-value pair of the map. For other types of parameters this field has no effect. When [`style`](#parameter-style) is `"form"`, the default value is `true`. For all other styles, the default value is `false`. Note that despite `false` being the default for `deepObject`, the combination of `false` with `deepObject` is undefined. |
+| <a name="parameter-explode"></a>explode | `boolean` | When this is true, parameter values of type `array` or `object` generate separate parameters for each value of the array or key-value pair of the map. For other types of parameters, or when [`style`](#parameter-style) is `"deepObject"`, this field has no effect. When `style` is `"form"`, the default value is `true`. For all other styles, the default value is `false`. |
 | <a name="parameter-allow-reserved"></a>allowReserved | `boolean` | When this is true, parameter values are serialized using reserved expansion, as defined by [RFC6570](https://datatracker.ietf.org/doc/html/rfc6570#section-3.2.3), which allows [RFC3986's reserved character set](https://datatracker.ietf.org/doc/html/rfc3986#section-2.2), as well as percent-encoded triples, to pass through unchanged, while still percent-encoding all other disallowed characters (including `%` outside of percent-encoded triples). Applications are still responsible for percent-encoding reserved characters that are not allowed by the rules of the `in` destination or media type, or are [not allowed in the path by this specification](#path-templating); see Appendices [C](#appendix-c-using-rfc6570-based-serialization) and [E](#appendix-e-percent-encoding-and-form-media-types) for details. The default value is `false`. |
 | <a name="parameter-schema"></a>schema | [Schema Object](#schema-object) | The schema defining the type used for the parameter. |
 
@@ -1181,7 +1181,7 @@ In order to support common ways of serializing simple parameters, a set of `styl
 | form | `primitive`, `array`, `object` | `query`, `cookie` | Form style parameters defined by [RFC6570](https://tools.ietf.org/html/rfc6570#section-3.2.8). This option replaces `collectionFormat` with a `csv` (when `explode` is false) or `multi` (when `explode` is true) value from OpenAPI 2.0. |
 | spaceDelimited | `array`, `object` | `query` | Space separated array values or object properties and values. This option replaces `collectionFormat` equal to `ssv` from OpenAPI 2.0. |
 | pipeDelimited | `array`, `object` | `query` | Pipe separated array values or object properties and values. This option replaces `collectionFormat` equal to `pipes` from OpenAPI 2.0. |
-| deepObject | `object` | `query` | Allows objects with scalar properties to be represented using form parameters. The representation of array or object properties is not defined. |
+| deepObject | `object` | `query` | Allows objects with scalar properties to be represented using form parameters. The representation of array or object properties is not defined (but see [Extending Support for Querystring Formats](#extending-support-for-querystring-formats) for alternatives). |
 
 See [Appendix E](#appendix-e-percent-encoding-and-form-media-types) for a discussion of percent-encoding, including when delimiters need to be percent-encoded and options for handling collisions with percent-encoded data.
 
@@ -1236,7 +1236,7 @@ The following table shows serialized examples, as would be shown with the `seria
 | spaceDelimited | true | _n/a_ | _n/a_ | _n/a_ | _n/a_ |
 | pipeDelimited | false | _n/a_ | _n/a_ | <span style="white-space: nowrap;">color=blue%7Cblack%7Cbrown</span> | <span style="white-space: nowrap;">color=R%7C100%7CG%7C200%7CB%7C150</span> |
 | pipeDelimited | true | _n/a_ | _n/a_ | _n/a_ | _n/a_ |
-| deepObject | false | _n/a_ | _n/a_ | _n/a_ | _n/a_ |
+| deepObject | false | _n/a_ | _n/a_ | _n/a_ | <span style="white-space: nowrap;">color%5BR%5D=100&color%5BG%5D=200&color%5BB%5D=150</span> |
 | deepObject | true | _n/a_ | _n/a_ | _n/a_ | <span style="white-space: nowrap;">color%5BR%5D=100&color%5BG%5D=200&color%5BB%5D=150</span> |
 
 ##### Extending Support for Querystring Formats
@@ -1961,7 +1961,7 @@ See [Appendix B](#appendix-b-data-type-conversion) for a discussion of data type
 | Field Name | Type | Description |
 | ---- | :----: | ---- |
 | <a name="encoding-style"></a>style | `string` | Describes how a specific property value will be serialized depending on its type. See [Parameter Object](#parameter-object) for details on the [`style`](#parameter-style) field. The behavior follows the same values as `query` parameters, including default values. Note that the initial `?` used in query strings is not used in `application/x-www-form-urlencoded` message bodies, and MUST be removed (if using an RFC6570 implementation) or simply not added (if constructing the string manually). This field SHALL be ignored if the media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of [`contentType`](#encoding-content-type) (implicit or explicit) SHALL be ignored. |
-| <a name="encoding-explode"></a>explode | `boolean` | When this is true, property values of type `array` or `object` generate separate parameters for each value of the array, or key-value-pair of the map. For other types of properties this field has no effect. When [`style`](#encoding-style) is `"form"`, the default value is `true`. For all other styles, the default value is `false`. Note that despite `false` being the default for `deepObject`, the combination of `false` with `deepObject` is undefined. This field SHALL be ignored if the media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of [`contentType`](#encoding-content-type) (implicit or explicit) SHALL be ignored. |
+| <a name="encoding-explode"></a>explode | `boolean` | When this is true, property values of type `array` or `object` generate separate parameters for each value of the array, or key-value-pair of the map. For other types of properties, or when [`style`](#encoding-style) is `"deepObject"`, this field has no effect. When `style` is `"form"`, the default value is `true`. For all other styles, the default value is `false`. This field SHALL be ignored if the media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of [`contentType`](#encoding-content-type) (implicit or explicit) SHALL be ignored. |
 | <a name="encoding-allow-reserved"></a>allowReserved | `boolean` | When this is true, parameter values are serialized using reserved expansion, as defined by [RFC6570](https://datatracker.ietf.org/doc/html/rfc6570#section-3.2.3), which allows [RFC3986's reserved character set](https://datatracker.ietf.org/doc/html/rfc3986#section-2.2), as well as percent-encoded triples, to pass through unchanged, while still percent-encoding all other disallowed characters (including `%` outside of percent-encoded triples). Applications are still responsible for percent-encoding reserved characters that are not allowed in the target media type; see Appendices [C](#appendix-c-using-rfc6570-based-serialization) and [E](#appendix-e-percent-encoding-and-form-media-types) for details. The default value is `false`. This field SHALL be ignored if the media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of [`contentType`](#encoding-content-type) (implicit or explicit) SHALL be ignored. |
 
 See also [Appendix C: Using RFC6570 Implementations](#appendix-c-using-rfc6570-based-serialization) for additional guidance, including on difficulties caused by the interaction between RFC6570's percent-encoding rules and the `multipart/form-data` media type.