These annotations, applicable to an entire library, are to allow users to specify the precedence of operation symbols, and the significance of layout in the so-called "offside" rule. Their primary purpose is to allow the omission of grouping parentheses and/or list separators in the input; but formatters may also exploit them to avoid superfluous parentheses in the display.
An approved set of parsing annotations and their syntax have not yet been worked out.