Used when opening a scene in the Editor to specify how a scene should be opened.
See Also: EditorSceneManager.OpenScene.
| Single | Closes all current open scenes and loads a scene. |
| Additive | Adds a scene to the current open scenes and loads it. |
| AdditiveWithoutLoading | Adds a scene to the current open scenes without loading it. It will show up as 'unloaded' in the Hierarchy Window. |