"Commission" means the utilities and transportation commission.

"File with the commission" means filed with the commission's executive secretary pursuant to WAC 480-07-140.

"Grays Harbor pilotage district" shall have the same meaning as in RCW 88.16.050(2).

"Person with a substantial interest" means:

(a) A pilot or a group or association of pilots licensed under chapter 88.16 RCW; 

(b) A vessel operator or other person using the services of a licensed pilot and paying pilotage fees and charges for such services or an organization representing vessel operators or persons; or

(c) Any other person or business entity that can show that a requested tariff change would be likely to have a substantial economic impact on its operations.

"Pilotage service provider" means a person licensed by the state to provide marine pilotage services in the Grays Harbor pilotage district or Puget Sound pilotage district.

"Pro forma adjustments" means a mechanism that gives effect for the test period to all known and measurable changes that are not offset by other factors.

"Puget Sound pilotage district" shall have the same meaning as in RCW 88.16.050(1).

"Rate design" and "rate structure" mean an arrangement or system of rates and charges that produces revenues necessary to recover the costs of service and support economic and social goals and policies.

"Rates" and "charges" mean prices for services that, when multiplied by the number of times a service is performed, determines the amount owed for the services.

"Serve" or "provide" means to deliver to commission staff and parties in a proceeding documents that are filed with the commission or documents that are not filed with the commission but are formally exchanged between parties.