An immediate operand specifies which halves of the 128-bit operands are multiplied. Integer constant operands are often pushed by separate instructions. Use of l-values as operator operands is particularly notable in unary increment and decrement operators. Addition is a binary operation, which means it has two operands. The number of operands of an operator is called its arity. The number of operands is the arity of the operation. This is in contrast to binary operations, which use two operands. Loop vectorization transforms procedural loops by assigning a processing unit to each pair of operands. Both used "big-endian" addressing of long versus short memory operands. Operators must be separated by whitespace from their operands. Many instructions have prefixes and/or suffixes referring to the types of operands they operate on. In 64-bit mode, instructions are modified to support 64-bit operands and 64-bit addressing mode. Chain input expects two operands and an operator. With a greater number of registers, instructions and operands, the machine code format was expanded. Descending precedence refers to the priority of the grouping of operators and operands.