As far as I am aware, all the 82xx calibres have unidirectional winding. The earlier 6xxx auto calibres have bidirectional winding, and I'm not sure why Citizen went to unidirectional. The local Citizen repair agent once told me he had quite a few 82xx's come in for "repair" as their owners claimed they kept stopping on them overnight. There was nothing wrong with them; he thought it was just that the owners weren't active enough during the day to keep the mainsprings sufficiently wound. He said he had never encountered that problem with the earlier bidirectional calibres.