Use a positional parameter in a macro definition if you want to change the value of the parameter each time you call the macro definition. This is because it is easier to supply the value for a positional parameter than for a keyword parameter. You only have to write the value you want the corresponding argument to have in the correct position in the operand of the calling macro instruction. However, if you need a many parameters, use keyword parameters. The keywords make it easier to keep track of the individual values you must specify at each call by reminding you which parameters are being given values.

See Positional operands for details of how to write macro definitions with positional parameters.