OptionalextentA string name for the bookmark.
OptionalthumbnailObject containing a thumbnail image.
Optionalurl?: stringThe URI pointing to the thumbnail image. Can be a URL or a base64-encoded image.
OptionalviewpointRepresents the location displayed on the map. If viewpoint is defined, ignore the extent. If viewpoint is not defined, use the extent property. For backwards compatibility, please save both extent and viewpoint properties.
Predefined bookmarks for use by the application. A bookmark is a saved map extent that allows end users to quickly navigate to a particular area of interest.
See https://developers.arcgis.com/web-map-specification/objects/bookmark/.