This icon is a plotting specification for imported text. It specifies the text box positioning in the plot frame of the Display Window / paper sheet. This is used to provide plot frames that can be filled with user defined text (e.g. to provide comments on complex plots).
The user text is provided by means of Text Plotting icons to be dropped in the plot frames containing this type of view.

The Annotation View icon can also be used for layout purposes, e.g. if no Text Plotting icons are dropped then an empty box will be created in the Display Window / paper sheet.
In fact, this icon combines three Metview 3 Views: TextView, EmptyView and ImportView (to be implemented).

The macro language equivalent is annotationview().