This command controls the display of the window captions. Normally a caption is only used if more than one window is shown on the display (split screen mode). But if the type is set to
screenshows a caption even if only one window is displayed. The default is ‘splitonly’.
The second form changes the text used for the caption. You can use all string escapes (see String Escapes).
Screenuses a default of ‘%3n %t’.
You can mix both forms by providing the string as an additional argument.