The 
Mapping Definitions section on the 
REST Expose
					Editor allows you to add, modify, or delete the custom node entries
				added to an element of a HTTP request or response. 
Note:  The option of adding a
					node is available for only for HTTP Header and it's children.
To add a node:
		 
		- 
				Select an element of a HTTP request or response.
			
- 
				Right-click the element, and then select Add node on the right-click context menu.
				 The Add Node dialog appears.
			
- 
				From the Type down-down, specify an element type for which you want
					to create the node such as Query String Parameter, Header, Body, or Cookie. If
					you select a PUT or POST verb on the Verb Association
					section, the Type drop-down will also include the Form
					Parameter type.
				 Note: 
						For a HTTP response, you can see only Header, Body, and Cookie in the
								Type drop-down. If you selected Header as Type, you can select content-type as the Header
							name from the drop-down list. 
 
- 
				In the Query String Parameter, Form
					Parameter, Header, or
						Cookie field, specify a value for the selected
					element. For example, Query1 for Query String Parameter. The
						Expression value field displays the specified
					parameter value. For example,
					${rest.queryparam['Query1']}.
				 
					The following example illustrates how to specify the
							Cookie field (a CHAR or
							LONGCHAR type). After choosing the Cookie field from
						the drop-down list, you set the cookie (as per the HTTP cookie standard) as
						follows: Set-Cookie: HSID=AYQEVn.DKrdst; Domain=.foo.com; Path=/; Expires=Wed,
							13-Jan-2021 22:23:01 GMT; HttpOnly Set-Cookie is a directive for the browsers to store the
						cookie. The Expression value field displays the
						following parameter value: ${rest.cookie['Set-Cookie:
							HSID=AYQEVn.DKrdst; Domain=.foo.com; Path=/; Expires=Wed, 13-Jan-2021
							22:23:01 GMT; HttpOnly']}. For more information on HTTP cookie specifications and setting a HTTP cookie,
						see the online information sources. Note: The field does not allow Java reserved words such as
							INT, CHAR, and
							BOOLEAN to be used as parameter names. 
- 
				From the Name drop-down list in the Body
					type, select a parameter. This list displays the input and output
					parameters of the operation (ABL routine) that is associated with the REST
					resource verb.
				 Note: The Name and JSON type fields appear when you
					specify the node type as Body in the Type
					drop-down. 
- 
				From the JSON type drop-down, select a data type. This list displays
					the OpenEdge supported JSON data types.
				 Note:  The JSON type drop-down will be enabled only when you specify your own
					parameter instead of selecting one of the parameters listed in the
					drop-down. 
 You can see the added node entry under the selected HTTP request or response element. The
			defined node context menu provides the options to edit (Edit
			node) or delete (Delete) the node.