d1 is d2 (default 1) tablespoon(s)/tablespoonful(s) [volume-unit], standard d3=m1 (default 1=15 mL),d4 dessertspoon(s),d5 teaspoon(s), d6 one ml measuring spoon(s).
x3 could be a particular spoon. x3 could also be for example the Australian standard (=lo sralo; 20 mL) or the unofficial unit of the Apothecaries' system of measures in the 18th century, equal to 4 drams or 1/2 fluid oz. It was more commonly known by the Latin cochleare majus (abbreviated cochl. maj.) or, in Apothecaries' notation, f℥ss or f℥ß.