x1 is x2 liter(s) [metric unit] in volume (default is 1) by standard x3.
See also merli, grake, mitre, dekpu, centi, decti, dekto, femti, gigdo, gocti, gotro, kilto, megdo, mikri, milti, nanvi, petso, picti, terto, xatsi, xecto, xexso, zepti, zetro.