imperial, order

詔 is composed of言(speech) and 召, the original form of 召 is the picture of two hands holding a spoon and taking up wine from a wine bottle to a bowl, depicts master(most likely an emperor) serving his guest(most likely the feudal barons) in ancient China, means the emperor summoning his subjects, so 詔 is used to represent the speech of the emperor which is announced to the general public.