Use a keyword parameter in a macro definition for a value that changes infrequently, or if you have many parameters. The keyword, repeated in the operand, reminds you which parameter is being given a value and for which purpose the parameter is being used. By specifying a standard default value to be assigned to the keyword parameter, you can omit the corresponding keyword argument operand in the calling macro instruction. You can specify the corresponding keyword operands in any order in the calling macro instruction.

See Keyword operands for details of how to write macro definitions with keyword parameters.