| Rank | Abbreviation | Meaning |
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| ***** | OPEN SEATING, OPEN SITTING. | Seats or tables are not assigned and will be occupied on a first-come basis.
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| ***** | OPEN SEGMENT, OPEN TICKET. | An airline ticket with no date specified.
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| **** | OPEN PAY, OPEN RATE. | A rate of payment or compensation that is subject to or will be determined by negotiation.
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| **** | OPEN BOARDING | . A system of boarding an airplane in which passengers are boarded by groups, usually determined by their time of booking or arrival at the gate, as opposed to being assigned seats.
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| *** | OPEN JAW. | A trip that has no air travel between two points on the itinerary. See also arunk.
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| *** | OPEN WATER. | Portions of the sea that are far from land in which a cruise ship might experience greater motion or rougher seas.
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| *** | OPEN TICKET. | A valid ticket that does not specify flight numbers, dates, or times. The holder of the ticket makes arrangements at a later date.
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| *** | OPEN SEATING PLAN. | An airplane seating strategy in which coach seats are filled at random by assigning passengers numbers based on their order of arrival at the gate. See also back-to-front system, reverse pyramid syste
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| ** | OPEN BAR. | Beverage service that is free for guests.
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| ** | OPEN SKIES. | Referring to an agreement between two countries allowing unrestricted air services between them.
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| ** | OPEN JAW WITH SIDE TRIP. | An open jaw itinerary with an additional roundtrip from one of the cities on the itinerary.
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| * | OPEN BATHROOM. | See exposed bathroom.
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