Clarify parameter use of schema or content

Author: darrelmiller

versions/3.0.md

@@ -932,7 +932,7 @@ Field Name | Type | Description
 <a name="parameterAllowEmptyValue"></a> allowEmptyValue | `boolean` | Sets the ability to pass empty-valued parameters. This is valid only for `query` parameters and allows sending a parameter with an empty value. Default value is `false`. If [`style`](#parameterStyle) is used, if behavior is `n/a`, the value of `allowEmptyValue` SHALL be ignored.
 
 The rules for serialization of the parameter are specified in one of two ways.
-For simpler scenarios, a [`style`](#parameterStyle) and [`schema`](#parameterSchema) can be used to describe the structure and syntax of the parameter.
+For simpler scenarios, a [`schema`](#parameterSchema) and [`style`](#parameterStyle) can be used to describe the structure and syntax of the parameter.
 
 Field Name | Type | Description
 ---|:---:|---
@@ -943,9 +943,9 @@ Field Name | Type | Description
 <a name="parameterExample"></a>example | Any | Example of the media type.  The example SHOULD match the specified schema and encoding properties if present.  The `example` object is mutually exclusive to the `examples` object.  Furthermore, if referencing a `schema` which contains an example, the `example` value SHALL _override_ the the example provided by the schema. To represent examples of media types that cannot naturally represented in JSON or YAML, a string value can be used to contain the example with escaping where necessary.
 <a name="parameterExamples"></a>examples | Map[ `string`, [Example Object](#exampleObject) \| [Reference Object](#referenceObject)] | Examples of the media type.  Each example SHOULD contain a value in the correct format as specified in the parameter encoding.  The `examples` object is mutually exclusive to the `example` object.  Furthermore, if referencing a `schema` which contains an example, the `examples` value SHALL _override_ the example provided by the schema.
 
-For more complex scenarios a [Content Object](#contentObject) can be used to define the media type 
-and schema of the parameter.  This option is mutually exclusive with the simple scenario
-above. When `example` or `examples` are provided in conjunction with the `schema` object, 
+For more complex scenarios a [Content Object](#contentObject) can be used to define the media type and schema of the parameter.
+A parameter MUST contain either a `schema` property, or a `content` property, but not both.
+When `example` or `examples` are provided in conjunction with the `schema` object, 
 the example MUST follow the prescribed serialization strategy for the parameter.