1, The full form of SX is Sint Maarten.

Sint Maarten (ISO 3166 code: SX) is a constituent country of the Kingdom of the Netherlands.It’s used on Regional ,Countries in Sint Maarten

Sint Maarten, part of the Kingdom of the Netherlands, is a country on the southern part of a Caribbean island shared with Saint Martin, a French overseas collectivity. Its natural features span lagoons, beaches and salt pans. The capital, Philipsburg, has cobblestone streets and colorful, colonial-style buildings lining its Front Street shopping area. The port is a popular cruise-ship stop.

2, The full form of SX is Simplex.

Simplex signaling (SX) is signaling in which two conductors are used for a single telecommunication circuit, and a center-tapped coil, or its equivalent, is used to split the signaling current equally between the two conductors. The return path for the current is through ground. It is distinct from a phantom circuit in which the return current path for power or signaling is provided through different signal conductors. SX signaling may be one-way, for intra-central-office use, or the simplex legs may be connected to form full duplex signaling circuits that function like composite (CX) signaling circuits with E&M lead control.

Simplex is also used to describe a powering method where one or more signal conductors carries direct current to power a remote device, which sends its output signal back on the same conductor. Phantom powering as used in audio is a form of simplex powering, as the return current flows through the ground or shield conductor.

It’s used on Academic & Science ,Electronics in Worldwide

3, The full form of SX is Skybus Airlines Inc.

Skybus Airlines Inc. was a privately held airline based in Columbus, Ohio, United States. It operated as an ultra low-cost carrier modeled after the European airline Ryanair, and aimed to be the least expensive airline in the United States. The business model was heavily reliant on flying routes where other airlines did not have direct flights, as Ryanair did in Europe, thus keeping competition to a minimum, and on flying into secondary airports, rather than heavily trafficked ones.

The airline also sold advertising space on the interior and exterior of its aircraft, as well as selling merchandise on board. Skybus applied for operating approval on January 1, 2005, received approval to operate on March 15, 2006, and FAA certification on May 10, 2007. It had been granted a waiver to begin ticket sales on April 24, 2007; Skybus’ first passenger flights out of Columbus began on May 22, 2007. Less than a year later, Skybus announced on April 4, 2008, that it would cease operations as of April 5, citing the lagging economy and rising fuel costs as causes

It’s used on Transport & Travel ,Airline Codes in United States