Mobile offshore unit with a buoyant hull and one or more legs that can be moved up and down relative to the hull. NOTE A jack-up reaches its operational mode by lowering the leg(s) to the seabed and then raising the hull to the required elevation. The majority of jack-ups have three or more legs, each of which can be moved
independently and which are supported in the seabed by spudcans.
Source: ISO 19905-1:202, Petroleum and natural gas industries – Site-specific assessment of mobile offshore units – Part 1: Jack-ups. Global Standards
Source: ISO 19900:2013, Petroleum and natural gas industries – General requirements for offshore structures. Global Standards