A legal equation is an infix sequence of operators and operands, such as . In addition to the usual operators described in § 21.9 and § 21.2 a considerable number of operators and operands peculiar to [B/D] are available, allowing access to [B/D] outputs. These are described in detail in the sections of chapter 21. A pair of round brackets is generally used to delimit an equation. In certain situations the delimiting pair of brackets, is redundant, and may be omitted. However, in doubt you should enclose an equation within round brackets - they cannot harm.