Responses from an API can include custom headers to provide additional information on the result of an API call. For example, a rate-limited API may provide the rate limit status via response headers as follows:
Add Response Header
To add a new header, select a response then select New Header from the menu at the top right. A new header UI is shown. Give it in a name and eventually fill in other fields. Then give it a schema or content. To select a schema click the link Add schema... at the bottom of the header UI. You'll be prompted with a wizard to select an existing schema or create a new one. To use a content type with this header, click the link Add content... at the bottom of this header UI.
Delete Response Header
To delete a response header, click the Delete header link from that header local toolbar.