Section 06.20.340 - Regulations, rulings, demands, and findings; service of notice(a) The department may adopt general regulations and make specific rulings, demands, and findings consistent with this chapter as may be necessary for the proper conduct of business and the enforcement of this chapter.(b) All notices required or authorized by this chapter to be given or served by the department may be given or served by registered mail and service is considered complete when a true copy is deposited in the post office properly addressed and stamped.