Definition of Z-axis

A Cartesian coordinate system specifies each point uniquely in a plane by a pair of numerical coordinates, which are the signed distances from the point to two fixed perpendicular directed lines, measured in the same unit of length. Each reference line is called a coordinate axis or just axis of the system, and the point where they meet is its origin, usually at ordered pair (0,0). The coordinates can also be defined as the positions of the perpendicular projections of the point onto the two axes, expressed as signed distances from the origin.

Underground Development (formerly known as Z-Axis) was a video game developer founded in 1994 and acquired by Activision in May 2002. In 2005, Z-Axis relocated to Foster City, California. In early 2008, the studio was renamed to Underground Development in response to changes in both direction and personnel.