The MAVEN Magnetic Field Investigation is Part of a comprehensive Particles and Fields Subsystem that will measure the Magnetic and Electric Fields and Plasma Environment of Mars and its Interaction with the Solar Wind. This Data Product includes Magnetic Field Observations in Sun-State and Payload Coordinates. Sun-State, SS, Coordinate System wherein the Primary Reference Vector, the X-axis, points from the Object, in this case Mars, to the Sun and the Secondary Reference Vector, the Y-axis, is in the Mars Orbit Plane, which is approximately opposite to Orbital Motion Direction, such that the Z-axis is Northward. The Observations Spacecraft Payload, PL, Coordinates are suitable for use in association with Measurements obtained by other Instruments on the Spacecraft. The Spacecraft Payload Coordinate System and the MAG Sensor Coordinate Systems are illustrated in Figure 21 of Connerney et al., 2015. The Text appearing here is also adapted from Connerney et al., 2015.