From Macross Compendium

A type of warp (or what is called super-light-velocity spatial displacement) navigation that can travel ultra long distances nearly instantaneously. To explain in simple terms, a fold transports a spacecraft in a very short amount of time by first swapping the location of the spacecraft with super dimension space or subspace, and then swapping the super dimension space with the space at the destination.
According to U.N. Spacy First Lieutenant Misa Hayase during Space War I (2009-2010), an hour passes in super dimension space as approximately ten days passes in normal space. The act of entering super dimension space is called a "fold in." When arriving at the destination, the act of leaving super dimension space is called a "defold" or a "fold out."
In recent years, the existence of obstacles called fold faults (or fold dislocations), the geometric-progression of energy consumption, and increased distances have become large barriers.